Before, sub-makes called by make were called without make knowing they
were sub-makes. This however led make's jobserver not do its tasks,
and the build process ended up with inefficient parralelisation. This
commit fixes this by applying the two ways the make manual tells
about: putting + to the start of the line (used when ndk-build is
invoked), and exchanging "make" with "$(MAKE)".

Before, make complained with messages like:

make[2]: warning: jobserver unavailable: using -j1.  Add `+' to parent make rule.

This complaint can now only been seen for openssl. openssl has issues
if make gets exchanged with $(MAKE): if exchanged, above error message
is multiplied for various subdirs of the openssl source tree.

On a 4 core box, "make -j 4" build time from "make clean_all" cleaned
source tree could be improved from 15:34 minutes to 10:45 minutes.
This means a speedup of 45%.

Currently translated at 43.8% (345 of 787 strings)

Currently translated at 40.0% (315 of 787 strings)

Currently translated at 95.1% (749 of 787 strings)

Squashed two translation commits to one

Currently translated at 48.7% (384 of 787 strings)

Squashed two translation commits to one

Currently translated at 43.8% (345 of 787 strings)

Currently translated at 56.6% (446 of 787 strings)

Squashed two translation commits to one

Currently translated at 59.7% (470 of 787 strings)

Currently translated at 3.1% (25 of 787 strings)

Currently translated at 39.8% (314 of 787 strings)

Currently translated at 49.0% (386 of 787 strings)

Squashed two translation commits to one

Currently translated at 11.4% (90 of 787 strings)

Currently translated at 30.7% (242 of 787 strings)

Squashed two translation commits to one

Currently translated at 23.7% (187 of 787 strings)

Currently translated at 42.0% (331 of 787 strings)

dcb91cf0 hacked around the biggest issue
this caused, but wasted a lot of CPU time and disk space  It also still
included a lot of other unwanted files.  This removes all of `doc/` except
the license, and also removes the server list.

Previous commit

70ea5d55 "Add support for limiting rotation of automatic face movement dir entitys"

by sapier has broken minetest's feature to open worlds. This was due to a
missing stack pop operation.

Thanks to @oleastre for reporting this bug and suggesting the fix.

or change the nametag text of players

3D Mandelbrot/Mandelbar
3D Christmas Tree
3D Mandelbulb
3D Cosine Mandelbulb
4D Mandelbulb
Plus corresponding julia set for each
Add credits for formulas
Rename parameter 'formula' to 'fractal'
Speed optimisations

Fix android build since commit

696148e2 "Fix Event implementation"

by @ShadowNinja.

Fixes #3444. Thanks @kwolekr for pointing out the fix.

* Horizontal and vertical are used wrongly. Use height and width because
	horizontal/vertical describes different things. Thanks @kilbith for pointing out.
* Update minetest.conf.example and settings_translation_file.cpp
* Correct maximum/minimum copy paste mistake.

using linear + binary search.

On non-windows platforms this just used a semaphore,
which meant that multiple calls to signal() would
result in wait() returning multiple times.

This is set to the XDG cache path where possible.
It's set to the app's cache path on Android.

Fix the type of the threshold value for mapgen.
The commit

a78dd7f2 "Fix spelling of noise_threshold"

has changed it to be read as int, but it can have non-integral values too.

Thanks to @kwolekr for pointing this out.

If rendered as markdown, lists need a blank line before them
so that they are recognized as such.

To terminate unwanted shadows from floatlands or realms above
Also add to LuaVoxelManip calc_lighting for use in mapgen mods
Remove the 2 argument calcLighting, mapgens now use the 5
argument form to specify the volumes for propagateSunlight and
spreadLight
In mgsinglenode replace calcLighting with setLighting and
clean-up use of tabs and spaces

On openSUSE luajit is not detected correctly.
This is because openSUSE is using a lua version suffix, like other Linux distributions do it also.
So the include directory is:
include/luajit-5_1-2.0

Now we do sudo apt-get update to download package sources.
This fixes travis build with the new GCE based infrastructure.

Closes #3427.
Closes #3426.