display correct track distance of shortened activities

[ChrizKu]

The distance is not corrected, after the gpx is cropped to the real cm part.
So often it's far to long, when participants include journeys to and from the cm in their tracks and truncate them afterwards.

[ChrizKu]

on the statistic site of the cities distance+duration values schould be given with less decimal places.
display of durations in x hour y sec would be nice…

[maltehuebner]

Thank you. This should now be fixed in #805.