Fix critical problem with Google activator: Bug #732652

Can't use Scheduled object in an async method with local variables
carried through to lambda -- reference is dropped in the interim.
Use Toolkit.RotatingButtonBox for remove recurring btns: Bug #732712

RotatingButtonBox uses a GtkStack for animating the slide, a better
choice than GtkRevealers.  This also fixes the bug where the buttons
appeared on the wrong side of the dialog (bug #732929).
Merge branch 'master' into wip/732029-gtk-312
More cleanup, removed GTK_312 conditional compilation