Under some conditions pom would report "waning" and then "full", show
higher percentages than it should, and get confused by DST. Fix.
Before:
2018.01.30: The Moon is Waxing Gibbous (97% of Full)
2018.01.31: The Moon is Waning Gibbous (100% of Full)
2018.02.01: The Moon is Full
2018.02.02: The Moon is Waning Gibbous (98% of Full)
After:
2018.01.30: The Moon is Waxing Gibbous (96% of Full)
2018.01.31: The Moon is Waxing Gibbous (99% of Full)
2018.02.01: The Moon is Full
2018.02.02: The Moon is Waning Gibbous (97% of Full)