v0.7.4b: Initial LibGDX commit! more details below:

Large sections of game logic are now working through libgdx instead of
android libraries. There is still work to do but this is the first
major step. Big changes include:
- Graphics code is now through LibGDX (except for text rendering)
- Initialization and screen-handling logic is now mostly through LibGDX
- Audio is now through LibGDX
- Input handling is now through LibGDX
- Most misc functions are now through LibGDX

SPD-classes/proguard-rules.pro

@@ -0,0 +1,19 @@
+-dontwarn android.support.**
+-dontwarn com.badlogic.gdx.backends.android.AndroidFragmentApplication
+-dontwarn com.badlogic.gdx.utils.GdxBuild
+-dontwarn com.badlogic.gdx.physics.box2d.utils.Box2DBuild
+-dontwarn com.badlogic.gdx.jnigen.BuildTarget*
+
+-keepclassmembers class com.badlogic.gdx.backends.android.AndroidInput* {
+   <init>(com.badlogic.gdx.Application, android.content.Context, java.lang.Object, com.badlogic.gdx.backends.android.AndroidApplicationConfiguration);
+}
+
+-keepclassmembers class com.badlogic.gdx.physics.box2d.World {
+   boolean contactFilter(long, long);
+   void    beginContact(long);
+   void    endContact(long);
+   void    preSolve(long, long);
+   void    postSolve(long, long);
+   boolean reportFixture(long);
+   float   reportRayFixture(long, float, float, float, float, float);
+}