Fixed the compilation errors in mod.cu

[ENH] OpenMPOp, doc and cleanup

Moved `#include <algorithm>` outside the `#if PY_MAJOR_VERSION >= 3` block.

The generated mod.cu contains a number of std::min and std::max. Including <algorithm> will remove the not-found errors from these two functions.

Fix errors in SparseBlockOuterSS c_code.

Mixed stuff: pep8, comments, doc, don't enable GpuConv*3D op by default at that module import.

[opt warning] fix gpu reduce opt warning.

This allow to move more computation to the gpu.

Float64

Add an option to desactivate conv2d_fft at the op level

3dfftconv

Don't make the kernels debuggable by default, but add those arguments to the 'nvcc-safe' list.

Conv gemm non-square kernel support

Extend documentation (plus small fix)