New Android library naming scheme and bug fixes.

Naming the Android libraries after their API level meshes better with existing Android tooling. The dessert names are not useful. This also changes the API level 13 library to be API level 15 (only 0.1% of the world uses API level 13) and fixes several bugs in the gesture handlers for the VisualizationView.

Finally, this makes it possible to build android_core with Eclipse. It still requires some manual work to import the projects, but it's possible.