First visible screen

For a given value of working, anyway.  Moves all old UI components into
build-excluded package, and all non-compiling components into a second
build-excluded package.
Re-implements GenericMainMenu and BasicMainMenu, now subclassing off the
Activity class.  No actual working logic inside the classes yet.
Merge branch 'master' of git@github.com:CovenantCS/AGM.git