Remove t3ver_swapmode code blocks
The different ways of versioning (element, page, branch) have
been defined to element versioning some TYPO3 version ago. With
TYPO3 4.7, those settings, especially the handling of the field
t3ver_swapmode has been removed from t3lib_TCEmain.
Since the default value of t3ver_swapmode is not -1 anymore,
but 0 instead, this will lead to inconsistent side-effects.
The solution is to remove all occurrences.