Fix two more problems in multi_dtype_cast_tests. Obviously not thinking straight today. Tests run now.

added python binding for cuda nd array dimshuffle
added test of the above
used the above to cover all four tranpose cases of test_cuda_ndarray.py:test_dot

fixed an issue where test_reshape in test_cuda_ndarray did not use the correct seed for random number generation

These tests were previously computing wrong values.

condition.

one that works on scalars.

previously introduced function for merging two slices.

Test that gemv are inserted into the graph. Disable the gemv test on complex as they don't get inserted.

re-use it for other optimizations.

optmized right now, and so they make no sense .. The code asks now for more
tests though.

interesting ones ?) with the disadvantage of making it slow