dungeon_overview adjustment

The dungeon_overview bits in the rm structure were being
clobbered by a run-length encoding save/restore because
they weren't taken into consideration.

This patch pulls that data out of the rm structure completely.

It also adjusts the run-length encoding checks to take the
candig bit into consideration and adds a comment to rm.h
reminding people to make run-length encoding adjustments
in save.c for any new bits that get added.

src/restore.c

@@ -999,6 +999,9 @@ boolean ghostly;
 	    trickery(trickbuf);
 	}
 	rest_levl(fd, (boolean)((sfrestinfo.sfi1 & SFI1_RLECOMP) == SFI1_RLECOMP));
+#ifdef DUNGEON_OVERVIEW
+	mread(fd, (genericptr_t)lastseentyp, sizeof(lastseentyp));
+#endif
 	mread(fd, (genericptr_t)&omoves, sizeof(omoves));
 	elapsed = monstermoves - omoves;
 	mread(fd, (genericptr_t)&upstair, sizeof(stairway));