(now at least <std> and <offset> are supported properly)
* instead of creating a TimeZone object whenever needed, we now
create it in tzset() and keep it around
* add tests for TZ to locale_test
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@40788 a95241bf-73f2-0310-859d-f6bbb57e9c96