Update lua_api.txt.

* Create UnitSAO, a common part between PlayerSAO & LuaEntitySAO
* Move breath to PlayerSAO & LocalPlayer
* Migrate m_yaw from (Remote)Player & LuaEntitySAO to UnitSAO
* Migrate m_yaw from Player to LocalPlayer for client
* Move some functions outside of player class to PlayerSAO/RemotePlayer or LocalPlayer depending on which class needs it
* Move pitch to LocalPlayer & PlayerSAO
* Move m_position from Player to LocalPlayer
* Move camera_barely_in_ceiling to LocalPlayer as it's used only there
* use PlayerSAO::m_base_position for Server side positions
* remove a unused variable
* ServerActiveObject::setPos now uses const ref
* use ServerEnv::loadPlayer unconditionnaly as it creates RemotePlayer only if it's not already loaded
* Move hp from Player to LocalPlayer
* Move m_hp from LuaEntitySAO to UnitSAO
* Use m_hp from PlayerSAO/UnitSAO instead of RemotePlayer

Modification of the emergeblocks internal state was not protected
by a lock, causing a race condition.
This can be reproduced by repeatedly running emergeblocks for an
already-generated section of the map (with multiple emerge threads).

* remove IGameDef from Player class, only LocalPlayer has it now
* move many attributes/functions only used by LocalPlayer from Player to LocalPlayer
* move many attributes/functions only used by RemotePlayer from Player to RemotePlayer
* make some functions const
* hudGetHotbarSelectedImage now returns const ref
* RemotePlayer getHotbarSelectedImage now returns const ref
* various code style fixes

* ClientEnvironment now uses UNORDERED MAP for active objects
* Use RemotePlayer and LocalPlayer everywhere it's possible
* Minor code style fixes
* Drop Client::getBreath() unused function

* Server/Client Environments now have an helper to cast Player object in the right type to use it
* Server: use RemotePlayer everywhere and remove previous added casts
* Client: use LocalPlayer where needed
* Environment: remove unused functions (getPlayers(), getRandomConnectedPlayer(), getNearestConnectedPlayer())

* LocalPlayer take ownership of maxHudId as it's the only caller
* RemotePlayer take ownership of day night ratio as it's the only user
* Pass getPlayerControl as const reference to prevent object copy on each call (perf improvement in ObjectRef::l_get_player_control call)
* getPlayerSAO is now only RemotePlayer call
* get/setHotbarItemCount is now RemotePlayer owned
* Server: Use RemotePlayer instead of Player object on concerned call to properly fix the object type
* PlayerSAO now uses RemotePlayer instead of Player because it's only server side
* ObjectRef::getplayer also returns RemotePlayer as it's linked with PlayerSAO

Also remove some unused parameters/functions

This is part 2 for 5f084cd9

Other improvements:

* Use the defined ItemGroupList when used
* make Client::checkPrivilege const
* inline some trivial functions
* Add ActiveObjectMap typedef
* Add SettingsEntries typedef

* This permit to improve performance on C++11 builds
* use some existing typedefs in tools maps
* minor code style changes

In lua_api.txt, make clear that 'place on' and 'spawn by' can be lists.

Adds several new ways that the plantlike drawtype mesh can be changed.

This requires paramtype2 = "meshoptions" to be set in the node
definition. The drawtype for these nodes should be "plantlike".

These modifications are all done using param2. This field is now
a complex bitfield that allows some or more of the combinations to
be chosen, and the mesh draw code will choose the options based as
neeeded for each plantlike node.

bit layout:
bits 0, 1 and 2 (values 0x1 through 0x7) are for choosing the plant
mesh shape:
  0 - ordinary plantlike plant ("x" shaped)
  1 - ordinary plant, but rotated 45 degrees ("+" shaped)
  2 - a plant with 3 faces ("*" shaped)
  3 - a plant with 4 faces ("#" shaped)
  4 - a plant with 4 faces ("#" shaped, leaning outwards)
  5 through 7 are unused and reserved for future mesh shapes.

bit 3 (0x8) causes the plant to be randomly offset in the x,z
plane. The plant should fall within the 1x1x1 nodebox if regularly
sized.

bit 4 (0x10) causes the plant mesh to grow by sqrt(2), and will cause
the plant mesh to fill out 1x1x1, and appear slightly larger. Texture
makers will want to make their plant texture 23x16 pixels to have the
best visual fit in 1x1x1 size.

bit 5 (0x20) causes each face of the plant to have a slight negative
Y offset in position, descending up to 0.125 downwards into the node
below. Because this is per face, this causes the plant model to be
less symmetric.

bit 6 (0x40) through bit 7 (0x80) are unused and reserved for
future use.

!(https://youtu.be/qWuI664krsI)

previously function used tonumber which returned float
this caused errors in large numbers and resulted in
obj-def-handlers being invalid when retrived from lua tables in c

* Move included json code to jsoncpp subdirectory

This is needed to avoid having to specify the minetest src directory
as a system include when fixing the json includes.

* Fix json includes

They used "", so that the compiler searches the project's directory
first. The result was that when compiling with a system jsoncpp,
the project's own version of json.h was still included, instead of
the system version.

The includes now use <>, so a system location, or one specified with
'-Ilocation' is searched only.

* Fix for jsoncpp deprecated function warning

When compiling with a newer version of jsoncpp (and
ENABLE_SYSTEM_JSONCPP=true), jsoncpp emits a warning
about a deprecated function that minetest uses.

This fallback to std::map & std::set for older compilers

Use UNORDERED_SET as an example in decoration and ore biome sets

Use UNORDERED_MAP as an example in nameidmapping

l_request_insecure_environment didn't ignore all whitespace in the
secure.trusted_mods config option.

Replaces std::remove with std::remove_if and the isspace function.

Modifications by est31: grammar fixes in doc + error messages and
a little style fix, no functional change.

This commit refactors the majority of the Mapgen settings system.
- MapgenParams is now owned by MapSettingsManager, itself a part of ServerMap,
  instead of the EmergeManager.
- New Script API functions added:
    core.get_mapgen_setting
    core.get_mapgen_setting_noiseparams,
    core.set_mapgen_setting, and
    core.set_mapgen_setting_noiseparams.
- minetest.get/set_mapgen_params are deprecated by the above new functions.
- It is now possible to view and modify any arbitrary mapgen setting from a mod,
  rather than the base MapgenParams structure.
- MapgenSpecificParams has been removed.

- Move mapgen creation logic out of EmergeManager and into Mapgen
- Internally represent mapgen type as an enum value, instead of a string
- Remove the need for a MapgenFactory per mapgen

Deprecate get_look / set_look pitch / yaw

Mgvalleys: Remove riverbed sand placement from base terrain generation
Riverbed material placement moved to MapgenBasic::generateBiomes()
Document fields and add note that the biome API is still unstable

This fixes value truncation (and therefore incompatibility) on platforms
with an LP32 data model, such as VAX or MS-DOS.

Gives a convenient way to check a player's password.

This entirely bypasses the SRP protocol, so should be used
with great care.

This function is not intended to be used
in-game, but solely by external protocols, where no
authentication of the minetest engine is provided, and
also only for protocols, in which the user already gives the
server the plaintext password.

Examples for good use are the classical http form, or irc,
an example for a bad use is a password change dialog inside
formspec.

Users should be aware that they lose the advantages of the SRP
protocol if they enter their passwords for servers outside the
normal entry box, like in in-game formspec menus,
or through irc /msg s,

This patch also fixes an auth.h mistake which has mixed up the
order of params inside the decode_srp_verifier_and_salt function.

Zeno-: Added errorstream message for invalid format when I committed

Note that the macro CHECK_FILE_ERR implements the code removed

Adds the particle option `collision_removal = bool`

Some particles are hard to use right now since they either go through
solid blocks (without collision detection), and with collision
detection enabled they (e.g. raindrops) would just stop dead on the
floor and sit there until they expire, or worse, scrape along a wall
or ceiling.

We can solve the problem by adding a boolean flag that tells the
particle to be removed if it ever collides with something. This will
make it easier to add rain that doesn't fall through your roof or stick
on the top of it. Or clouds and smoke that don't go through trees.

Particles that collide with this flag are marked expired
unconditionally, causing them to be treated like normal expired
particles and cleaned up normally.

Documentation is adjusted accordingly.

An added bonus of this patch is that particles can potentially collide
many times with nodes, and this reduces the amount of collisions to 1
(max), which may end up reducing particle load on the client.