[TASK] Optimize TCA additions and ext_tables.php

* Separate TCA overrides from definitions
* Move all possible TCA definitions from ext_tables.php
  to overrides
* Cleanup ext_tables.php by consolidating if statements
* Wrap ext_tables.php calls in closure to not interfere
  with following extensions
* Add dependency to TYPO3 6.2.1 as overrides requires this version

Change-Id: I5aec6477c7b8a5156f13c2ac6e6436a8921fbd30
Resolves: #58006
Reviewed-on: https://review.typo3.org/29537
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer