An early refactor. Some ideas became clearer as
development continued. Now the various phases are much
clearer and more easily reusable.
Also added a ton of tests!
Change-Id: Ic8f0a70c8222370352e63533b329c40457c0903e
We modify the XML of layouts and AndroidManifest enough
that it warrants we operate on the tree in memory.
These files are never very large so this should be fine.
Change-Id: I5d597abdb3fca2a203cf7c0b40fcd926aecb3137