Allow installation to external storage.
Update README to include Leaflet licenses.
Refactor leaflet.html to spin off JavaScript code.  Add
Marker.Rotate.js from https://github.com/shramov/leaflet-plugins and
arrowhead SVG icon.
Correct licenses to include Marker.Rotate.js
Add speed line to layouts.
Update strings.
Add support for displaying speed and bearing info, because why not?