DateTimezone::setTimeZone() throws exceptions.

And accepts an array of identifiers.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5712 2fea6a4d-a838-0410-917b-93a53c48e9d2
Example.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5713 2fea6a4d-a838-0410-917b-93a53c48e9d2