* _check_view_map will not raise an error if multiple inputs have the same id,
and one of the outputs has a view_map to one of those two inputs

respects to inputs and outputs, with Ops which fail to define the proper
view_map and destroy_map

* Grouped all the view tests into single class

* fixed view map bug in TanhRnnGrad (Op defined in a test case)

seed_rng() should be called with no parameters as much as possible. If you want
stuff to be deterministic, define the THEANO_UNITTEST_SEED env. var

Nightly build should probably define THEANO_UNITTEST_SEED though