Ensure p13n transportation is in a valid state.

Fixes #172.
Make route polylines prettier.

Make walking black/gray. Reduce edge smoothing.
Tweak walk colors some more.

Lighter gray ensures berry stem still stands out in front of walk leg path.
Bugfix: account for url prefix when linking to app root.
Fix: prevent line wrapping in css, not code.
Bugfix: template indentation had been changed.