When in edit/delete mode, revertLayers has to be called
when another handler is clicked on.
Reorder code that enable/disable edt/delete handlers.
Add draw:deletestart and draw:deletestop events.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/edit/EditToolbar.js
Extend changes to enable/disable in Draw.Feature.js.
Merge pull request #247 from manubb/master

Edit/delete handler bug.