Feature request: pull full spec from header file

[dev-zero]

One of the problems we encountered with handwritten INTERFACE declarations is the divergence of the C declaration and the Fortran declaration which doesn't get caught by any tool. In that example Shroud helps already by generating the INTERFACE part (and needed wrappers, like the string), but one still has to maintain the declaration in 2 different files.

It would be awesome if Shroud could pull the full declaration automatically from a C header file and one would simply have to name the function/struct to import. It seems that pycparser would be suitable for supporting C.