[TYPO3-core] RFC: #7642: Page tree Filter use wrong div for collapse

[Steffen Kamper]

did i used a bad title for this thread? May be people don't understand what 
this patch is for.

This patch does a lot:
* implement docheader for page tree
* changed pics for filter (thx to Jens Hoffmann)
* correct the css-bug with the csh icon on the right side
* deliver better icons for the arrows (used in left menu also)

vg  Steffen