TimeZone handling for Perl 6.
Parses common offset strings and returns an Int value.
Returns a TimeZone object representing the zone passed to it. These objects provide an .Int call, so they may be used directly as the :timezone parameter for a DateTime object.
This will support any timezone listed in the Olson database.
The $datetime is used to calculate the offset depending on Daylight Savings Time rules for the given Time Zone.
If $datetime is not passed, it assumes DateTime.now();
A shortcut for: $datetime.in-timezone(timezone($name, $datetime));
This is very much under development, and currently only the tz-offset() subroutine is supported.