Fixed popover.hide not to break chaining.

This means that the monkey-patched destroy() was never necessary,
so this has been dropped too.
don't let mousedown on actions propagate

This prevents a click on the toolbar from deactivating the current
editor.
mousedown on popover does not propagate

This prevents the event from reaching aloha and causing the editor
to deactivate, which allows clicking on popovers without the popover
closing on you.