first order streams with NHD plus

[jmccreight]

With the FRNG test domain using NHD:

• over half of the reaches are 1st order (9552/18226=.524)
• 50 of these 1st order reaches have upstream (1st order reaches)

Right now, in the code:

• qlink1 (the upstream flow from each reach appears to be output to file)
• flow from upstream reaches is treated as zero.

1. Do we want to output so many zeros (is there something more informative than outputting qlink1?)
2. We should fix 1st order reaches with upstream reaches.

I also noted several 2+ order reaches (2,5,6) with zero flow, but this may have been a more pointed Route_Link.nc specification issue.