Added support OpenBSD, NetBSD, DragonFly OS

Fisable glfw only when it is not found and not external.

Replaced old dwarf model

Note that HDR exposured possibilities are not used on this example...

Replaced by medieval 3d assets

Added: data to CharInfo struct
Added: LoadFontData()
Added: GenImageFontAtlas()
Removed: LoadFontEx()
Removed: LoadTTF() [internal]
Some code tweaks

- GetImageData()
- GetImageDataNormalized()

...by emscripten glfw javascript implementation

Reviewed: GetImageData()
Reviewed: ImageFormat()

ImageDraw() code tweak

Reduced draw calls

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.

Temporary measure to fix a breakage on FreeBSD.
See #551 for more details.

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

I don't know if this actually works, but it compiles, which is good enough for CI.