TYPO3 Core

One of the initial JS files with prototype
called common.js (which was moved from
typo3/js/common.js into EXT:backend
with the namespace removal) was previously
used for calls using Prototype AJAX
calls.

The file was now used in two areas:
- backend.php - containing an instance of
the mother object "TYPO3" used for the
backend scaffolding via ExtJS.
- old Prototype trees (loaded in DocumentTemplate)
introducing an API when using prototype as AJAX handler
when errors from AJAX requests occurred (was piped
to the ExtJS debug bar).

Cleaning up the common.js file leads to
a) moving the "mother object" TYPO3 into backend.js
where all other ExtJS initialization for the TYPO3 Backend
is done.
b) "old" Trees using AJAX without the hook
for show error messages.