Refactor InfoBox

[nateirwin]

Use a container pane to position InfoBox. This way you won't have to constantly reposition the InfoBox as the map is panned/zoomed, etc. You will have to "reposition" the container pane, but it should be lighter weight and more extensible and adaptable in the future.

This will also allow you to turn inertia back on for Leaflet maps. Currently it is turned off because the move Leaflet map event is not called when the map is thrown.