clean up audio chiptunes support

... and switch from debug build to release

Trying to simulate Oculus Rift CV1 rendering without the device... for
Debug pourposes.

...on Android

Develop branch integration

Fix mistake in the make file

Moved all external libraries used by raylib to external folder inside
raylib src. Makefile has already been update and also the different
includes in raylib modules.

Android build system has been simplified and now is included in src
folder, like other build systems.

Trying to find the best way to integrate Oculus support into raylib,
making it easy for the user...

Not functional yet...