Hide popover before destroying it.

Otherwise it thinks it is visisble and refuses to show up again on
click.
Namespace the show and hide events so they clean up.

The show and hide events, bound via delegation to the editor itself, did not
clean up properly, so there was this ever growing list of hide/show events on
every math element, which likely caused severe performance issues. Adding
a namespace ensures that it is cleaned up when .bubble is off()'ed.
Formatting change in comments, no functionality.  dead code cleanup
Replace aloha-editable-activated with -created.

Also unify the various event handlers all bound to the same event into one.
Use -created event rather than -activated, this code need only run once,
and in our old code where the editor was never deactivated, that is how it
worked anyway.