I can't get preference fragments working in my world (mostly because
nested PreferenceScreens don't open when clicked on and the workarounds
for that are too complex) so next best thing is to fix alerts to work on
top of prefs activity. That involves creating a new transparent activity
that subclasses XWActivity and has a DelegateBase subclass. Launching an
alert is then just a matter of passing DlgState into the new activity
via an Intent, at which point everything Just Works. Button clicks are
returned via an intent as well.
Merging of AndroidManifest.xml files meant the dbg flavor was getting
its C2D_MESSAGE permission and the main flavor's, which on recent OS
versions meant it couldn't be installed. Use substitution from gradle to
fix.
