BUG: Fix BinShrinkImageFilter for different input/output image types.

The input iterator needs to be defined over the correct type.

Change-Id: I4a47762b4cfdfbea56b144ed576064122c65eb18
Merge branch 'BinShrinkOutput_release' into release

Change-Id: If7645c3e24f5d93058262b9f0d9c24ab192ca17c