Fixed regression of XML processing of IP values.

The arlut.csd.ganymede.server.xmlfield parsing code neeeded to be
updated to create IPAddress objects from Strings, and I missed
that before.
Typo in StringSelector header comments.
Implemented focus highlighting and tab-to-scroll in embedded objects.
Added black border around StringSelector lists when focused.
Added scroll to focus for checkbox fields in client.

Note that JcheckboxField is *ancient*, and it's still using the
JDK1.0 (!) method of handling events through direct subclassing
of the event handling methods, rather than using listeners (!!)
Took focusability out of StringSelector for empty list boxes and titles.
Made some fixes to the no-longer-used JcheckboxField JDataComponent
Left focus highlighting alone on text field in StringSelector
Made checkboxes in containerPanel scroll-to-focus
Improved error messages in IPAddress parsing