using Variable's comparison operators

Need to swap inheritence order for class ScalarVariable: inherit
_scalar_py_operators first, then Variable

inc_subtensor/set_subtensor.

* changed inheritance order of TensorVariable to include _py_operators before
Variable, so that TensorVariable can use the comparison operators defined in
_py_operators

inc_subtensor/set_subtensor, as the previous implementation is now deprecated.

import the version of theano and nothing else. In some case we could import the version from another project.

the Theano type

refactored TensorSharedVariable test of shared options to be able to reused them for CudaNdarrayShared.

to check for input aliasing and removed the transitivity assumption on the
aliasing.

mutable or borrowed

Make PatternSub hangdling of allow_multiple_client with dictionnary that don't define it to default to the value of the parent nod instead of False.

Also fixed tensordot to accept numpy syntax for axes.