[BUGFIX] Restore Link Creator and Image Editor

The change-set also makes some adjustement in the Thumbnail API
to be more understandable.

Change-Id: I8739633924bdbd430fc9e92dc0e9b4d9ddb3f574
Releases: 3.0
Resolves: #61128
Reviewed-on: http://review.typo3.org/32664
Reviewed-by: Fabien Udriot <fabien.udriot@ecodev.ch>
Tested-by: Fabien Udriot <fabien.udriot@ecodev.ch>