pep8
In the ShapeFeature, convert x.shape[1] to Shape_i. This will help compare shapes.
Add ShapeFeature.same_shape, that try to compare 2 var shapes.
Add local_useless_inc_subtensor.

Remove the IncSubtensor when we can infer all the shapes are the same.
Make opt local_useless_subtensor convert to subsample when we reverse.
Disable opt in some case discovered in new tests crash with the new opt.
Merge pull request #2070 from nouiz/opt_inc_sub

Opt inc sub