[TYPO3-core] make the tree collapsable

[Ingo Renner]

Ingo Renner wrote:

> currently this is t3skin only

but yes, we can of course make it available for non-t3skin, too. That 
involves:

* removing the border background image from the original border.html
* replacing border.html with the patched noborder.html from t3skin
* use that new border.html in the classic skin and t3skin - removing 
redundancy


what you think?
Ingo

-- 
Ingo Renner
TYPO3 Core Developer, Release Manager TYPO3 4.2