Add note about numbering in leap-months.
Add stub for output of builder.
Add tests for isLeapYear, creation, based on ending.
Add test for range based on year division.
Add check for in-bounds leap-week-period.
Add test for illegal state builds.
Rename member to better match call.
Add constructor and wire up builder.
Return types changed to appropriate type.
Implement era-returning methods.
Implement prolepticYear
Add comments and implementation for existing factories.
Add missing era-based factories.
Add remaining factories.
Add factory stubs to AccountingDate.
Comment and implement of basic factories.
Add ChronoLocal / ChronoZoned factories.
Increase year range to ensure quad-century is covered.
Update test to use prev (was calcing for next year)
Implement isLeapYear()