edit: Report unit loss and gain properly for unit key 'O'

edit: Report unit loss and gain properly for unit key 'O'

Print a message describing the actual change.  Necessary to give the
deity a chance to catch unexpected changes, e.g. a player boarding a
ship right before the deity edits it.  Watching out for such changes
is especially important with non-interactive edit.

Code already sends bulletins.  Also report news.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>