Add test for get_diagonal_subtensor_view on the GPU.
pep8
Make DiagonalSubtensor work on the GPU.

This need a Theano PR https://github.com/Theano/Theano/pull/1436

This is tested indirectly with the test for conv3d.
Merge pull request #2 from nouiz/gpu_diagonal_subtensor

Gpu diagonal subtensor
Add Op.__str__ fcts.
Make the IncDiagonalSubtensor work on the GPU.

This need https://github.com/Theano/Theano/pull/1437 PR to get merged to work.
Allow to create the op with default parameter value.
Merge pull request #3 from nouiz/gpu_inc_diagonal_subtensor

Gpu inc diagonal subtensor and optimization refactoring.
Tell where to use this repo.