add some stub files. This can wait.

The architecture of the binding will be

ProcMesh: process / domain decomposition
LocalBuffer: the local fft buffer, can be viewd as double / complex
        need an indexing convention (transpose etc)
        also does local -> global index translation (with offsets)
        and takes care of the padding in case of r2c / c2r

Plan: plan. __init__ takes two LocalBuffer objs
    execute takes two LocalBuffer objs (new array)
    exception if __init__ and execute Localbuffers are in compatible.

That's all we need.

No need for numpy.fft compat layout. this is all parallel.

Remeber pfft and fftw shall be compiled with -fPIC, or linked shared.

TODO: Bundle PFFT and patched FFTW source code. compile with mpi4py
compilers (mpi4py.get_include mpi4py.get_config etc)
PFFT can be as a github submodule (autoconf can be a pain)
FFTW shall be source tarball or files (think about it)