monster name formatting

While testing monster summoning by using a debugger to force the
outcome, I saw "the renegade Angel of <foo> appears in a cloud of
smoke" as if only one such creature existed.  Trying to change
that to "a renegate Angel" pointed out some problems:  type names
like Angel, Green-elf, and Uruk-hai fool an() into using "the"
because of their capital letter.  Fixing that was a bit of a hack
and worked for Green-elf and Uruk-hai but not for Angel because
it has the eminion extension so uses priestname() instead of the
guts of x_monnam().  Fixing that involved more hackery and now I
feel unclean, but it seems to be working.

It wasn't as noticeable as it might have been because most of the
time that "the Angel of <foo>" or "the priest of <bar>" was shown,
the caller is requesting "the" rather than "a/an".

doc/fixes37.0

@@ -1,4 +1,4 @@
-NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.573 $ $NHDT-Date: 1624053070 2021/06/18 21:51:10 $
+NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.575 $ $NHDT-Date: 1624322667 2021/06/22 00:44:27 $
 
 General Fixes and Modified Features
 -----------------------------------
@@ -547,6 +547,8 @@ using a bullwhip to snatch a wielded cockatrice corpse from a monster when not
 	panic during final cleanup
 make fire-command autowield an appropriate launcher and add fireassist boolean
 	option to toggle the assistance off
+Angels and priests were always described as "the {Angel,priest,high priest} of
+	<deity>" when first two should have been "{an Angel,a high priest}..."
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository