[TASK] Add helper function for array handling

Adds a helper functions for easier handling of arrays.
New class t3lib_utility_Array adds a method to reduce an
array by a search value.
New method in t3lib_extMgm adds a method to add new items
to a TCA select list at a spcified position.

Change-Id: I589294525a7eacc7af6e54c5b78f5ee411574f12
Resolves: #26069
Relates: #22408
Reviewed-on: http://review.typo3.org/1647
Reviewed-by: Alexander Stehlik
Tested-by: Alexander Stehlik
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn