* Removed SDL2 source.
* Updated gradle.
* Updated SDL2 Java support glue code.
* Increased minimum supported Android API version to 24.
* Updated required asset files for Android app.
* Added proper tag for Android logging.
* Added SDL2 hint to make BGFX work on Android.
* Fix compile for Android, set API to 24
* Update Android Studio project to API 24
* Fixed project file to latest Android Studio
* fix build with gradle alone