Add Replay Control slider and change slider markup

This doesn't hook up the Replay Control slider - it just creates the UI
element and changes the way the existing Speed slider is implemented (with
the corresponding value displayed right above the slider handle and the
label below the slider).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Have the progress slider track the time

So far manual changes to the slider make no difference, but the slider is
updated as data comes in from the server.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Rewrite the map application

This decouples updating (the AJAX calls into the server running
visualize.js) and drawing the updates on the map, resulting in a much
more fluid drawing of the map.

- getMore calls /update via AJAX; it provides an end time to the server
  and stores the path segments into an array.
- the drawing function then decides which of the paths need to be shown on
  the map.
- the ReplayControl slider isn't fully functional, yet - that needs more
  work.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Address most jshint complaints

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Fix Replay Control

Now the visualization continues at the right spot when the user lets go of
the slider handle.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Allow start and stop of path drawing / updates

Also remove some debugging output.

This is not perfect as the delay in getting all the AJAX data still can
cause a jerky user experience.

Also, in my testing I occasionally get unexplained lines to (0,0) GPS
coordinates.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Make it less likely to have to wait when using the replay control

Downloading more data per AJAX call might cause a slightly longer delay at
the start (but this is likely hidden by Google Maps delays).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Bring back the map centering that was lost in the rebase

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Merge pull request #29 from dirkhh/mapChanges2

Map changes2