fix a bug in DebugMode when their is only c_code(no perform()) and that we do inplace operation on the inputs. This would cause False error warning.

as well !)

resulting in "undefined variable" error.

Added unit test test_inc_subtensor.py (almost identical to test_incsubtensor) to
test the new (undeprecated) inc_subtensor / set_subtensor functions

Oops, bug fix in (and streamlined) error reporting when updating shared variable (implemented with James)

left-padded if the user asked NOT to store intermediate results (this should be
the default-case for shared variables)

updated documentation related to verify_grad and TensorType

Very confused why this optimization is necessary...