Fixes invalid setting of lifetime in caches pagesection (and rootline in Typo3 6.x). 

In typo3 6.X a hook is used which is safe.

In typo3 4.X an XCLASS is used to extend t3lib_TStemplate - might conflict with other extensions.

Fixes http://forge.typo3.org/issues/50231 and http://forge.typo3.org/issues/39295.