Add GpuKernelBase, a mixin class to help deal with kernels in C code for compyte.
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.
Make the GpuKernelBase C code PY3 compatible.
Fix kernel compilation under stupid cuda overloading rules.
Use a ternary op since it seems the cuda compiler cannot resolve overloads by going through simple typedefs.
Merge pull request #1625 from abergeron/gpueye_ocl

GpuEye compyte