Merge: Support for Java arrays, Java libs on Android and Google Cardboard head tracking

Use the same approach to copy the "libs" dir to the Android project than the "res" dir.

Extern Java types for primitive arrays is a bit tricky to convert to JNI format. For example, `Object[]` in Java is represented by `[Ljava.lang.Object;` in JNI format, and `int[]` is `[I`.

Add some primitive Java arrays, will add more as needed. Will also need to update jwrapper to use those.

The last commit hints at my next demo. It is mostly generated with jwrapper.

Pull-Request: #1079
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>