dataengines/weather: Specify forecast link for wetter.com
Currently 'wetter.com' doesn't provide a link to the place forecast, just to their homepage.
We can build and offer such link using the place id, so the behavior is similar to other providers.
Before: http://www.wetter.com
After: http://www.wetter.com/place/DE0002265.html
BUG: 449933
FIXED-IN: 5.91.90