fix broken core-extension types

                   
|Q            |A  |
|---          |---|
|Bug Fix?     |yes|
|New Feature? |no |
|BC Breaks?   |yes |
|Deprecations?|no |
|Fixed Tickets| #28  |
|License      |MIT|
                   
The only BC is that Time now always uses UTC. but using a timezone was broken anyway in this case.