Move the common I/O routines to a separate file.
Interface for 'geophy.bin' model file.

This is an unformatted (binary) Fortran file that contains surface field inputs
for the GEM model.

Note: assuming that the geophy file was generated on a big-endian system, such
as AIX.
Set the time axis to the dates of validity.

This is necessary to read multiple forecast times from the same file.
Hack to check for possible negative forecasts, and allow for fractional number of forecast hours.
Merge branch 'geophy'
Merge branch 'fix_forecast'