Remove unsused code (minor)

Compile the inner fct in scan only once per instance.

Conv3d2dinplace

Add config option to specifiy cublas library name.

Assorted gpuarray work.

[MRG] Fix crash when specifing march in cxxflags.

GpuEye compyte

Use a ternary op since it seems the cuda compiler cannot resolve overloads by going through simple typedefs.

Cleanup

Refactor it to make a registry op c code.

The new Gpu back-end reuse those 2 fct.

Convert GpuEye to be a real compyte op.  This is, where possible, a direct translation of the original code and does not reflect the preferred style.