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.

Fixed a minor mistake that made it appear as if the inventory
is serialized multiple times - once per each variable. In fact
it is serialized once per each node.

This reverts commit 60dc01dc.

This fixes issue #3773

Having a non-power-of-two image broke the Android app.

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.

If the default value of a setting was empty,
it previously generated a trailing space.

Currently translated at 61.3% (483 of 787 strings)

(Merger of five commits)

Currently translated at 49.5% (390 of 787 strings)

(Merger of three commits)

Currently translated at 47.0% (370 of 787 strings)

(Merger of two commits from the same author)

Currently translated at 37.3% (294 of 787 strings)

Currently translated at 46.6% (367 of 787 strings)

Currently translated at 65.5% (516 of 787 strings)

Currently translated at 33.9% (267 of 787 strings)

Currently translated at 30.4% (240 of 787 strings)

Currently translated at 45.9% (362 of 787 strings)

Currently translated at 52.7% (415 of 787 strings)

Currently translated at 42.4% (334 of 787 strings)

Currently translated at 69.1% (544 of 787 strings)

(Merger of three commits)

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

Android had a linker error since commit:

31e0667a "Add Lua interface to HTTPFetchRequest"

Fixes #3766. Thanks to @MoNTE48 for reporting the bug.

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.

Newest leveldb commit breaks build.
With no fix in sight, there is no other way
than to fall back to the last working leveldb
revision, and hardcode it.

Workaround for upstream bug

https://github.com/google/leveldb/issues/340