This directory points to datasets needed to test transient crops at the
smallville 1x1 resolution.

Eventually, this testmods directory may be able to be removed. However, it is
needed for now because we do not have an 1850 surface dataset for crops - see
comment 3 in <http://bugs.cgd.ucar.edu/show_bug.cgi?id=2010>. So, for now, we
are pointing to a year-2000 surface dataset for the transient run. This is a
perfectly acceptable thing to do, but making it work out-of-the-box would
require introducing some ugly one-off logic that I wanted to avoid.

However, we may need to keep this testmods directory around in order to point to
the landuse_timeseries file for this test case, which differs from typical files
in that it only goes up to year 1855 rather than 2000.
