Copy constructor for timezoneJS.Date objects

[mnpenner]

var newDate = new timezoneJS.Date(oldTimezoneJsDateObj)

Constructs a new date but discards the timezone information from the old date. I'm presently working around the issue by constructing it this way:

var newDate = new timezoneJS.Date(oldTimezoneJsDateObj, oldTimezoneJsDateObj.timezone)

[longlho]

This issue shouldn't be hard to fix. Can you provide a simple test case for this?