Minor miscellaneous fixes
These fixes:
- persist Absolute.valid flag if included in reading submitted to Calculation.calculate()
(needed so front end can resubmit readings to calculate absolutes without wiping out user-specifiedvalidflaggs) - handle H_SQ, H_SV, and H_Dist
(needed so we can duplicate data with legacy sncls until the Edge data migration is 100% complete) - fix the channel parser for IAGA2002 files
(we received IAGA2002 files from outside collaborators recently that broke our parser; this fixes that) - fix some SNCL mapping issues
Edited by Erin (Josh) Rigler