CommonRenderer.java Added loadResources method with empty implementation, which is run upon context loss.

* Shader.java Added abstract initGLStates.
* Mesh.java Added method for validating the vertex data.
* PerInstanceParams.java Renamed drawFirst to firstVertexIndex.
* Added javadoc comments and minor code cleanups
* MyRenderer.java override loadResources to handle when gl context is lost.
* App.java Resource loading now happens here.