[BUGFIX] Form shows Fatal Error in Frontend

This resolves the wrong instantiation of all classes
that contain uppercase characters within a certain
class name part, by adding the lowercased versions
to the class alias map.

Fixes: #40850
Releases: 6.0

Change-Id: I973393a5476e5b0ee8a2500117de636e43513666
Reviewed-on: http://review.typo3.org/16362
Reviewed-by: Thomas Maroschik
Reviewed-by: Mattias Nilsson
Reviewed-by: Ingo Pfennigstorf
Tested-by: Ingo Pfennigstorf
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel