plus
Returns a copy of this HebrewLocalDate with the specified number of days added.
This method adds the specified amount to the days field incrementing the month and year fields as necessary to ensure the result remains valid. The result is only invalid if the maximum/minimum year is exceeded.
For example, 2008-12-31 plus one day would result in 2009-01-01.
This instance is immutable and unaffected by this method call.
Return
a HebrewLocalDate based on this date with the days added, not null
Parameters
days
the days to add, may be negative
Throws
Date
if the result exceeds the supported date range //TODO