* Replace string by-val passing with const reference
* Fix code style
* Remove redundant `int table` definition and indentation level

Throwing a LuaError calls destructors as it propagates up the stack,
wheres lua_error just executes a longjmp.

Increase maximum spawn altitude to reduce spawn issues.

Fixes #3764

This function could be used to steal insecure environments from trusted mods.

This still only supports 256 characters, but that's because
Irrlicht's clipboard handlers don't support wide characters.

keymap_console opens a full window for chat history browsing.

This reverts commit 60dc01dc.

This fixes issue #3773

Lower water table where base humidity is low.
Alter heat and humidity to compensate for river humidity and altitude
chill.
Correct misuse of surface_max_y in generateTerrain.
Remove sand trails in the water at river mouths.
Remove river water below water_level.
Correct heat/humidity calculations where noises are less than zero.
Correct heightmap errors as much as possible.
Make humidity calculations more readable.

Fixes #3765

In the calculation of y_start,
when 'column height max' was large it caused
nmin.Y + max_height > nmax.Y - max_height
Now, in this situation y_start is set to the
midpoint between nmin.Y and nmax.Y

Limit y0 and y1 to between nmin.Y and nmax.Y,
otherwise index calculation, which has no checks for limits,
places them at unwanted locations in the voxelmanip

As stated in this forum thread [1], I noticed that there is a
2 second interval in which inventory changes are shown on the
client. @yyt16384 found the source of these 2 seconds:
m_nothing_to_send_pause_timer is set to 2.0 every time there
are no changes to make, but this timer is not reset when
SetBlockNotSent or setBlocksNotSent are invoked. So in worst
case, the changed block will be sent over 2 seconds too late.

With this change, changed inventories are updated almost
immediately, but it causes additional connection load.

Fixes #3719
Closes #3753

This allows mods to perform both asynchronous and synchronous HTTP
requests. Mods are only granted access to HTTP APIs if either mod
security is disabled or if they are whitelisted in any of the
the secure.http_mods and secure.trusted_mods settings.

Adds httpfetch_caller_alloc_secure to generate random, non-predictable
caller IDs so that lua mods cannot spy on each others HTTP queries.

Instead, perform a POST request with post_data.

Closes #3748

Fixes #3378
Closes #3751

Also, downgrade the error to a warning.

Previously you could steal a secure environment from a trusted mod by wrapping
request_insecure_environment with some code like this:

local rie_cp = minetest.request_insecure_environment
local stolen_ie
function minetest.request_insecure_environment()
	local ie = rie_cp()
	stolen_ie = stolen_ie or ie
	return ie
end