[TYPO3-ect] Integrate ajax with extensions

[Christoph Koehler]

el, headers and stuff like that.
>
> I haven't thought of that. But I have solved it by being nasty. TYPO3
> calls my pi1, and I just output my stuff (echo ...) and then exit()
> after I'm finished. I know there is no other output that TYPO3 should
> generate for me anyway, so it works. :)

Haha, that's what I do :) Check for the config option, it it's there, do  
ajax stuff and then return out.