(Barely) usable styling for edit widgets in info pane.

Also set max height for the pane itself, so it gets a scroll bar.
More complete edit schema for sample data.

If nothing else, this cuts down on spurious widgetry from the JSON editor.
Use bootstrap's icons in JSON editor.

This does involve storing its font files.  Sigh...
Scroll edit pane to the top when loading a new feature.

Otherwise, if the user scrolled down, they wind up in the middle
of the new feature's properties, which is almost certainly not what
they want to be first looking at.