TYPO3 Core

Hey all,

this is a first step into consistency for AJAX calls in the TYPO3 Backend. It consists of two parts. The server-side component (typo3/ajax.php with an TYPO3AJAX instance from typo3/classes/class.typo3ajax.php)) and a client-side part, connected to the AJAX objects of the prototype framework that is extended by generic responders (typo3/js/common.js) to handle errors. I also rewrote the pagetree to work with the new interface as a first example.

A small introduction, more detailed information and an example on how to write more AJAX code is also attached.

• Filetree is still using old code and therefore is not working.
• Nice error outputting (with a generic notification area in the Backend) is still missing.
  I am waiting for the first feedback until I fix these two things, which should be both trivial.
  (issue imported from #M7096)