Contents:
- fix h5py/netCDF (Issue #31) & simplify formats loading order, new shortcut
epygram.open - set stack limit unlimited in init_env() (for FA/spectral transforms)
- freeze version of eccodes until full externalisation of falfilfa4py, compiled with consistent eccodes
- backwards compatibility of gauss_rgrid2namelists
- Add uv2psikhi function (#32)
- fix spectral property for vector fields