R_op for ZeroGrad + tests

Add unravel_index and ravel_multi_index

Dilated causal convolution

add decsription for rnnblock

Fix a memory leak in theano

Use E_PADSHAPE flag in GPU Incsubtensor

ExtractDiag cleanup #5633

Make it more clear error when not enough GPU memory. fix gh-6397

test MRG random stream with device=cuda and target=cpu

Fix unit tests for CEnumType.

Gpu stack follow up

This should expose an issue in GpuIncSubtensor

Improve tests for meta-optimizer

Update introduction.txt

Make test pass in Python 3

Links outdated.

Move the test to the GPU directory and mimic device=cuda in another test following the current change.