added ability to create invalid moments
fixing jshint error from rebase
using NaN instead of 0
fixing conflicts
wip
merging in develop
parse flags
some cleanup
fixing isValid() definition
more cleanup
simplify empty handling
tests and a working isDSTShifted
merge develop
skippedInput + trailingInput = unusedInput
among invalid moments, prefer the first one, regardless of score
tests for invalid date string
fixes for review
adding missing file
merging develop
attempt to address @ichernev's concerns