TYPO3 Core

The attached patch does the following minor things:

- in the list view, running tasks appeared disabled if their current run is their last run. An improved check makes sure the task still appears as running.
- in two places, the code used a hard-coded error status instead of t3lib_FlashMessage::ERROR
- a couple of variable initializations were added where appropriate
- image clear.gif was removed, as it is unused (using svn delete)

(issue imported from #M12406)