Fix for oversize bounds when Trimming.

Take the min of start bounds and new bounds + 1 to avoid claiming
area that doesn't exist within the original image. Accomodates fix
for off-by-one when actually trimming and doesn't result in expanded
images when no trimming was necessary.
Merge pull request #293 from sansumbrella/trimmings

Fix for oversize bounds when Trimming.