DOF info fixes
- this should fix the DOF info issues mentioned in https://bitbucket.org/hudson/magic-lantern/pull-request/635/correct-dof-handling
- added menu options for CoC and diffraction
- this should also fix the conflict with top bar on 5D2/50D, http://www.magiclantern.fm/forum/index.php?topic=9852.msg146974#msg146974