[TASK] Remove class.tx_cms_layout.php from EXT:cms/layout

Class in unused and marked for removal in TYPO3 CMS 6.2

Resolves: #61232
Related: #61218
Releases: 6.3
Change-Id: I720020e5d36045f2cba3535b9bbb043c34f33715
Reviewed-on: http://review.typo3.org/32459
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>