Fixed how Dates work transitioning from negative to positive. Year 0000 represents 1 BCE/BC (as indicated in ISO 8601) and Year -0001 is 2 BCE/BC, etc. Also changed the rata die epoch.
Updated leap seconds and UNIXEPOCH to reflect the shift in rata die epoch.
Condensed the string definitions of Date and DateTime.
Fixed dayofweek to reflect the new epoch.
Updated tzdata files