[TYPO3-core] minor skin issue: wizard icons (see #2493)

[Martin Kutschker]

Ingmar Schlecht schrieb:
> Hi Martin,
> 
> Martin Kutschker wrote:
> 
>>Please have a look at the new icons attached to bug #2493.
>>
>>And also have a look at the fix for the skinning issue.
>>
>>Me thinks only the call to the skinning API was missing.
> 
> +1 based on reading the code and looking at the icons.

BTW, while creating this small fix I noticed that it and *all* skinning 
only works if the skinning extension is either a system or a global 
extension. Why? Because all paths are relative to typo3/.

This patch is in sync with other code (so it uses TYPO3_typo3 without any 
further check).

Masi