Initial commit of post-processing codes for C-LAMP experiments

add_total_fields - modifies model output netCDF files to add fields computed
from fields within the files.

h1_summary - computes means and standard deviations of hourly output netCDF
files, creating two new netCDF files (one for the means and one for the
standard deviations) for each month by hour of day.

h1_summary2 - the same as h1_summary, but it uses more memory to read in more
timeslices at once, so it may be faster on some machines.