[TASK] Remove support for ImageMagick 4 and 5

IM4 and IM5 support has been deprecated and is scheduled for
removal in TYPO3 4.6.

Change-Id: Ib7610a3666e764e32c854fb04b5d80ef3030dad3
Resolves: #24146
Reviewed-on: http://review.typo3.org/1989
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers
Reviewed-by: Steffen Gebert
Tested-by: Steffen Gebert
Reviewed-by: Jigal van Hemert
Tested-by: Jigal van Hemert