OR-365 remove unused image module
OR-365 explicitely forbid images that have a too little side
OR-365 Work around a round error that bring a bug on FireFox

Ensure that the selection height and width can never be larger
than the image height and width
Merge pull request #442 in OR/rse from ~MBAILLY/rse:OR-365-crop-behaviour to master

* commit '53f401b67b2bad45f3a74932835f7bb2c5c8f8b3':
  OR-365 Work around a round error that bring a bug on FireFox
  OR-365 explicitely forbid images that have a too little side
  OR-365 remove unused image module