Reviewed: GetImageData()
Reviewed: ImageFormat()

ImageDraw() code tweak

Added note idea on ImageFormat() for future redesign (to support
16bit-32bit pixel-formats)

Not used in raylib this mechanism

Replaced by fabs() that seem to work ok

It seems TCC was not casting correctly int values to float in some
specific situations

Added android_native_app_glue module to raylib compilation instead of
compiling it as static lib at apk generation.

Did this ever work? Surely, doesn't look like it...

Not sure if this ever worked, but now it at least compiles.

Release, unless we are in a Git repo, then it's Debug.

From 2019 64bit support will be mandatory to publish an Android app.
Google plans to require that new apps target Oreo (API level 26) in
August of 2018.

On OpenGL 1.1 only is supported for 32bit RGBA textures

Please do this whenever necessary. And adapt it before releasing a new
RC. The RC should already have the correct one.

Now defaults to Clang, ARM64 and API 21

This reverts commit 2d6fb5c628068757387525e190c3afdbe33ae9c6,
and adds a fix for Alien::raylib's test failures.

The tests failed because the resulting static library didn't reexport
GLFW symbols. As a fix, we now have GLFW create a CMake "object library"
target that we can link with both the static and shared raylib.

This is arguably ugly... Proper fix would probably be a GLFW upstream
object library target.

Closes #536.

This reverts commit 0adb4b67de6dfe3f7a0a557130dffc3b8f4d6a43,
because it failed tests for Alien::raylib:
http://www.cpantesters.org/distro/A/Alien-raylib.html

Review raylib_icon resource

Makes it easier to support Wayland later on.

We need the CMake stuff for wayland configuration.
Otherwise, we would have to replicate that ourselves.
This is the full 7ef34eb06d tree except
for tests/ examples/ and docs/

Panders to the idiosyncrasies of my work flow:
I have my raylib build directory mounted as a VirtualBox vboxfs for use
with my Linux VM, but vboxfs doesn't support symlinks, while raylib shared
library versioning on Unix expects symlinks to work.
If this happens, library versioning is now disabled on Unix with
an error message instead of just failing the build.