Remove all remaining GParamSpec name and blurb strings (and fix
indentation while we're there), and add G_PARAM_STATIC_STRINGS to all
paramspecs that were lacking it.
NmtNewtForm is an NmtNewtWidget, but previously it was only realizing
its child, not itself, which is technically wrong (though it had no
noticeable effect until get_realized() was added).
Use newtPopWindowNoRefresh() rather than newtPopWindow() when
destroying a form, since often we have to destroy and then almost
immediately after re-create the same form, and we don't want that to
be visible.
The main "connect" and "edit" windows set the "escape-exits" flag, but
that just closed the form without exiting the app, leaving the user
trapped. Fix this by emitting a signal when the form quits, and
catching that. (And now we don't need to watch the "clicked" signal on
the quit buttons, since they have the "exit-on-activate" flag set.)
The keyboard focus was getting reset to the first widget any time a
widget changed validity, because the form wasn't updating priv->focus
when it should have.
