ANDROID: Remove old feature requirements

These don't seem to work as intended as they cause the play store to limit us to 23 devices.
ANDROID: Install to internal by default

Remove android:installLocation="preferExternal" as it is not needed for such a small app.
ANDROID: Update the NDK toolchain to 15
GRAPHICS: Stencil for grim shadows [OpenGLS]
GRAPHICS: Transpose view/model matrices correctly
GRAPHICS: Add shadow mode to grim actors [OpenGLS]