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

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.

Removed OpenAL and GLFW3 dependencies on building.
Reviewed platforms and flags

- Removed useless templates
- Reviewed all Makefiles
- Rework some code for Android support
- Added resources to advance template