Added a new decorator and tagged a few opts for optimization when using the gpu or optimizer=fast_compile.

Register to the gpu tag more opt, as we don't have all the other case on the GPU otherwise in fast_compile.

fast_compile.

Mixed

fix gh-2099

Make optimization more deterministic

[MRG] fix gh-2091

Completed TODO in tensor.py:as_tensor_variable which said to use the App...

Conflicts:
	theano/tensor/tests/test_basic.py

Why do it use weakref anyway for the Link?

Opt inc sub

When optimizer=None, we had a crash at Theano import time.

THEANO_FLAGS=optimizer=None,device=gpu python -c 'import theano'

Fix crash in python 3.

Completed TODO in as_tensor_variable which said to strip off leading bro...

Doc

Move Assert to the GPU in both back-end.

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