reject: Exempt bulletins on relation change with deity

reject: Exempt bulletins on relation change with deity

Bulletins notifying on a relations change can be rejected just like a
telegram from the country initiating the change, except for one
inconsistency: telegrams from deities are exempt, but bulletins on a
relation change by a deity aren't.  Inconsistent since rejecting was
added in Merc Empire.

Change setrel() to treat relation change bulletins the same as tele()
treats telegrams.

Should not normally matter, because the reject command doesn't let you
reject deities.

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