Remove and replace redundant interfaces

Many of the interfaces are exact duplicates of ones from `GLSurfaceView`
and, as far as I can tell, add no value. While integrating the latest
code into the downstream [Rajawali](https://github.com/MasDennis/Rajawali) framework, I found these interfaces to
be a nuisance. Our classes, which already implement the `GLSurfaceView`
interfaces, were not considered valid to the `GLWallpaperService`.

`GLWallpaperService` has been modified to accept the `GLSurfaceView`
interfaces. The local duplicates have been removed. This will break
backward compatibility for projects that use the local variant, but the
fix is easy: replace the "`GLWallpaperService.`" prefix with a
"`GLSurfaceView.`" prefix or tweak the import statements.

## Alternate Implementation ##
#25 is a variation of this pull request that maintains backward compatibility and merely deprecates the duplicate interfaces. However, it is more verbose and "ugly". Only one or the other should be merged.