Keep viewing stats until they're deleted
Corrected some scope initialization problems

Discovered that some items were being initialized at each presentation
request rather than on application startup. Whoops.

That's been corrected and stats are now accumulated until they are
manually reset.
Track more useful info about slide viewing

* Keep track of individual slide views instead of a cumulative time per slide.
* Save a timestamp for each view so we can collate them into a path through the material.
* Save the slide that the presenter is on so we have an idea of where in the presentation other slides are useful.
Version bump
Fixed notes spacing.
Merge pull request #105 from binford2k/features/stats_updates

Track more useful info about slide viewing