Make the op_lifter take a list and lift again the Sum op.

Add test for it.

Do not include now the Prod op as there is failing test.
Remove compilation warning.
Make gpugemv and gpugemm work correctly when the back-end don't support inplace.

add assert too.
Add GpuDot22
Implement GpuAlloc(memset_0=True) as in the old back-end.
Use the class for for __str__.

The new Gpu back-end reuse those 2 fct.
Do not move scalar elemwise to the gpu.
Add Shape_i c code for the new gpu back-end.

Refactor it to make a registry op c code.
Remove debug code leftover and fix problem on windows raised by code review.
Small optimization for GpuAlloc and memset_0
Remove double list.
Merge pull request #1626 from nouiz/gpu

Assorted gpuarray work.