1. Delete the extjs component of t3skin.
2. Add extjs component of t3skin based on ExtJS 4.
3. Adapt t3skin/ext_tables.php.

Change-Id: I70d7b63e570456e79c5bc747a12263eefc4c2fac
Resolves: #32187
Releases: 4.7
Reviewed-on: http://review.typo3.org/7094
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter
Tested-by: Stefan Neufeind