Addition histogram added. getHistogramData generalized to include
a field parameter in EcriService.js. RiverSegmentList.js includes
additional fields, calls to the EcriService to obtain histograms
and inform the DOM which id's they belong to (#histogram1 and
 #histogram2, resp). Also there is a call to getHistogramData2
with additional key:value pairs to trigger rendering
in LocationReportView. MapLayerUpstreamSegmentView.js calls
the upstream segment function with Strahler order 4; this seemed
to be a workable compromise. map.html includes additional
divisions for the second histogram and the new template.
The histograms should be interpreted properly. These are
frequency histograms of segments (1min grid squares) with
data in the displayed interval. It might be preferable to
show the actual counts rather than the proportions. The
units should be gone over carefully (it would be nice
if the data guardians were forthcoming--but we leave this
for now).