Fixes #4323.

* Multiline strings
* Table-concat instead of String-concats
* string.rep instead of loop-concat
* string.format %q instead of manual quotation by gsub
* Assert writeable files
* Generate new settings_translation_file

Avoids unreachable code linter warning by moving generation code
(of minetest.conf.example and settings_translation_file.cpp)
out of dlg_settings_advanced.

Due to passing the settings, also it avoids reading the settings file twice.

Instead of activating the code by changing the active if-clauses,
its activation is now done by uncommenting the loadfile() statement.

Commit 4503b5 did not update the android build script.

Increase maximum length of tiled node rows from 2 to mapblock size.

'maxwear' has been deprecated for over 3 years
Add spaces around '=' nearby

Add an [opacity:<r> texture modifier. Makes the base image transparent according to the given ratio. r must be between 0 and 255. 0 means totally transparent. 255 means totally opaque. Useful for texture overlaying.

If compiling according to a C++ version before C++11, then define
std::to_string ourselves.

Add a to_wstring version as well

As std::to_string() for floating point types uses %.6f as floating
point format converter, instead of %G, it needs special care.

To preserve ftos() behavior (which is expected to use the %G format
converter), it no longer uses to_string().

If a mod is disabled, or upgraded without sufficient backward compatibility,
then entities it has put into the world become unknown, and continue moving
around, but are completely unrecognisable.

This change allows the player to see their type, and therefore which mod is
or was responsible.

Also add note for 64-bit Windows users

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

Fix height check comparison from '>=' to '>'.
Fix getHeight() for schematic decorations to account for
'deco place center y' flag and for how normal placement
sinks schematic 1 node into the ground.

Jungletrees were not being placed at y = 46, y = 47 despite
having an acceptable 16 nodes of height above ground surface.

When the 'flat' and 'trees' flags were moved into mgv6_spflags they
were left in mg_flags in an attempt to support old mgv6 worlds. However
their appearence in mg_flags causes confusion, also, later, old-world
support was found to be broken for mgv6 worlds with 'notrees'.

This commit cleans up the mess and comes a month after a thread warning
of the change, and explaining the required action, was posted in the
news subforum. Only old mgv6 worlds with 'flat' or 'notrees' are
affected, a small minority of worlds, the required action being
correctly setting these flags in mgv6_spflags.

Disable a section of the 'map settings manager' unit test which is to
be changed as it is causing problems for pull requests.

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.

Combine texture_overrides.txt and sections of lua_api.txt

* Update README.txt

As of Ubuntu 16.10, libpng12-dev is replaced with libpng12-0, since libpng12-0 is available in 16.04 repositories, I think that needed to be changed.

Also I changed 'git-core' to 'git' for fedora users, keep it consistent with the ubuntu/debian instructions.

* Update README.txt

Instead of trying to manually parse the output of 'git show' which can be different across different git configurations, properly use the 'git rev-parse' command that is intended for this purpose.

This little update is due to a packaging problem when uploading on play store. They don't permit to re upload an APK with same version code.
This case was a fail on openssl packaged version which was old and rejected by Google but they don't remove the APK then i should increase the version code to permit having it on play store

For consistent horizontal sprite structure when seen from front and back
Fix code style

Recommend mod screenshot size in lua_api.txt
Adjust displayed screenshot size of texture packs
Document texture pack files in lua_api.txt

core.check_player_privs accepts as first argument a name or player object, but just tested for a string.
This caused crashes inside builtin, when being passed any unexpected types.

This provides a better (duck-typing like) test, better error reporting.

When a CavesNoiseIntersection tunnel intersects a river place biome
'riverbed' nodes in tunnel entrance instead of biome 'top' nodes.

Use the setting "profiler.load" to enable profiling.
Other settings can be found in settingtypes.txt.

* /profiler print [filter] - report statistics to in-game console
* /profiler dump [filter] - report statistics to STDOUT and debug.txt
* /profiler save [format [filter]] - saves statistics to a file in your worldpath
	* txt (default) - same treetable format as used by the dump and print commands
	* csv - ready for spreadsheet import
	* json - useful for adhoc D3 visualizations
	* json_pretty - line wrapped and intended json for humans
	* lua - serialized lua table of the profile-data, for adhoc scripts
* /profiler reset - reset all gathered profile data.
	This can be helpful to discard of any startup measurements that often spike during loading or to get more useful min-values.

[filter] allows limiting the output of the data via substring/pattern matching against the modname.

Note: Serialized data structures might be subject to change with changed or added measurements.
	csv might be the most stable, due to flat structure.

Changes to the previous version include:

* Updated and extended API monitoring
* Correct calculation of average (mean) values (undistorted by idleness)
* Reduce instrumentation overhead.
* Fix crashes related to missing parameters for the future and occasional DIV/0's.
* Prevent issues caused by timetravel (overflow, timejump, NTP corrections)
* Prevent modname clashes with internal names.
* Measure each instrumentation individually and label based on registration order.
* Labeling of ABM's and LBM's for easier classification.
  Giving several ABM's or LBM's the same label will treat them as one.
  Missing labels will be autogenerated based on name or registration order.
* Configurable instrumentation and reporting. Skip e.g. builtin if you don't need it.
* Profile the profiler to measure instrumentation overhead.