Closes the generator menu after making a selection
Added capabilities to generators and saved the currently active
generator

Each generator has a set of "capabilities."  The capabilities will be
used to correctly construct the overview mode.

For each capability, a new item is added to the overview mode.

E.g.: freeFormStepping will bring up the impress like editor
2dStepping will bring up the reveal like editor
cannedTransitions will bring up the list of canned transitions that can
be applied.

Having all capabilities will bring up all editors (although free form
stepping and 2d stepping would naturally conflict with one another)