[TASK] RTE: Code cleanup

Remove references to simple ExtJS methods.
Simplify names of JavaScript files.
Make script dependencies explicit.

Releases: master
Resolves: #63381
Change-Id: I474578810fa2d991a5f4743a5cde3efb642d1545
Reviewed-on: http://review.typo3.org/34714
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>