Fixed broken content type headings when class name contains an underscore.

  (No, I don't use underscores in class names, except when doing crazy
   namespacing stuff for multiple FeinCMS base classes sharing the same
   content types...)
Merge pull request #484 from DrMeers/master

Fixed broken content type headings when class name contains an underscor...
Add an implementation of Array.lastIndexOf to ie_compat.js