UI naming consistency:
* DopeSheet -> Dope Sheet. No need to glue the words together. 

Only changed comments and UI strings, no functional changes. Request by Dalai Felinto. 

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56603 954f8c5b-7b00-dc11-b283-0030488c597c