in lieu of Ready Item Editor

in lieu of Ready Item Editor

We're trying to prevent folks from using the item attribute editor in the
unified interface when the volume pane is still updating its information
(i.e. building the copies to feed to the attribute editor), so that a
given editing widget isn't ripped out from under staff while its being
used.  This change removes the heavy-handed Ready Item Editor button and
instead tries to more gracefully manage the editor state based on change
and keypress events.  Also change the color scheme for a disabled editor
from red to light pink.

Signed-off-by: Jason Etheridge <jason@esilibrary.com>