Have filenames in streams use years from $DATM_YR* rather than hardcoded min/max

This is especially true for datm because the list of files is long. But, it could apply to other data models as well. Currently the minimum and maximum years for the filenames in streams is hardcoded in. The actual years that will be used is set by $DATM_YR* variables. But, for instance for CLMGSWP3v1.Solar you have this...

`$DIN_LOC_ROOT_CLMFORC/atm_forcing.datm7.GSWP3.0.5d.v1.c170516/Solar/clmforc.GSWP3.c2011.0.5x0.5.Solr.%ym.nc`

The downside I see to this is that at initialization it will open each of the files in the list in turn and get the time information from them. This can take awhile so it seems more prudent to have the list shortened so that it only has the filenames of the years it's actually going to use.

It will also make a difference when downloading the files. If the full range is given it will download the full list, even if the user wants one or two years. I actually recommend to users that they use $DATM_YR* to get a shorter list of files using check_input_data --download, and then after they've been downloaded to increase it to download another section.