Fix problems for release

Fix docgen fails due to GPU not available

keep stack trace in optimizations of nnet folder

Fix test that fails on the buildbot

(#4196) increase the tolerance of test_gc_never_pickles

Kmap

Fix typo in docs

Impossible to compile a COp

[OPT FAILURE] Fix gh-4131

flake8 misc/tests/*.py

Fixes https://github.com/Theano/Theano/issues/4199

Make the python code for Gemv also check for the need to initialize the output with beta=0

Skip the gpuarray tests is init_gpu_device == gpu*

fixed rng_mrg int32 overflow, just throw out the error when it overflows

Fix typo and clarify CNMeM config documentation

Make sure imshp and kshp are constant

GpuBatchedDot: streams implementation (WIP)

Fix typo and clarify cuDNN config documentation