added the percentage of the trajectory length
solved some string formatting issues
removed debug stuff
moved the HR segmentation into the ActivityModel since we will need it in other
places as well
Moved the blocks in the view into separate template files. This means we don't
have code duplication in the separate graphs/map/summary pages etc
switched from ids to classes, since I'm planning on reusing the selectors
- Renamed the ActivitySpeed etc to `SpeedSummary`
- Made Trajectory, Activity, and ActivityFile an instance of a new trait
 HasSummaryData that provides access to these summary* values
added a dummy class representing power zones
- updated the snippets to work with the HasSummaryData instances. In
  particular, the class that renders the summary of the view can accept any
  hasSummary instance and display its data
- switched to class selectors to select the blocks in the view
- switched to classes in the view as well
- updated the graphs stuff. We can now display summary information
fixed the issue with the javascript stuff not being included
correctly. Apparently you cannot youse <script src="..."/> but you *HAVE* to
use <script ...></script>
added filtering and taking subtrajectories
Connecting the selected stuff in the frontend to the backend. Still work
remaining here though. The wiring is a bit clumsy now. See to improve that