[calendar] very_short_weekdays fallback to datatype-date-format langage data

Both shortWeekDays and weekDays will be localized at least datatype-date-format
is available in specified language. Fix #1796.
[calendar] Tweak the indent
Merge branch 'fix1796' into dev-master
[calendar] Update HISTORY
[calendar] Build
Merge branch 'dev-master' into dev-3.x