Add the land mask to the list of variables to ignore (2D data only).
Fix the way the time string is written out so that the call to mjulian2greg isn't so often. Also add Rory as an author.
Make some fairly significant changes to accommodate the Met Office
Unified Model data.

- Check for the presence of the input fields being requested in the
input struct to avoid finding out that the last field in vars doesn't
exist in data.
- Change the way the alternative coordinate arrays are used to
accommodate subtleties in the parallel code in MATLAB.
- Update the debugging figure at the end to be a bit more resilient.

I haven't checked that these changes don't break the interpolation of
the NCEP data, so that needs doing.