Highlight active diameter in inspector.
Wrap node captions on to multiple lines.

This is a very naive implementation; always breaks at every space, regardless of line length.
Text measuring and fitting needs to be added later.
Currently uses a hard-coded 10px line height. Will need to respect font-size in the future.
Also, remove usage of alignment-baseline because this still SVG attribute isn't implemented in Firefox.
Update radius of node overlay.