update to 2.1.0
move DayOfWeek to a java enum
move Month to a java enum
enrich MonthOps APIs
enrich WeekOps API
enrich YearOps API
enrich MonthOps / YearOps api
add missing tests for io.lamma.Date
add dayOfMonth and dayOfYear method to next / previous for MonthOps and YearOps
rename pom to dom
rename poy to doy
add more API docs for the library