Documentation of source data.  sources-list2.html is most complete, though some editing happened later in final report Appendix A.

Fix label: HSRL "Depol Ratio" is really HSRL Dust Mixing Ratio.  Data had been changed but label wasn't.

gather_separated(): Return separate pieces of ribbon which overlap the timerange - don't pretend they're contiguous in time.

Pull time/lat/lon/altitude/heading/etc. for early+late times from corresponding fields in MetNav file, specified with -metnav option.