Use default implementations of several methods.
Use super version of range when possible.
Correct calculations from ofYearDay
Restrict scope of methods (unlikely to be directly useful to
implementers).
Use super for daysUntil, monthsUntil
User super version of until(date, unit) for everything except year-based
values (due to its use of months, and the varying number of months in
this case).
Remove the minusXxxx methods.
Use super version of plusDays.
Restrict scope of plusMonths and plusYears
Raise scope of method to match methods from super.
Implement resolvePrevious
Restrict scope to match super definitions.
Change getYear() to be required getProplepticYear()
Add explanatory comment.
Implement rangeAlignedWeekOfMonth
Override lengthOfYearInMonths (most things that use it are also being
overridden, given the changing number of months in a year).
Make "last month" more explicit.
Change getLeapYearsBefore to be Long based.
Shorten toEpochDay calculation.
Add shortcut for cases when handed destination class.