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.

include/patchlevel.h

@@ -14,7 +14,7 @@
  * Incrementing EDITLEVEL can be used to force invalidation of old bones
  * and save files.
  */
-#define EDITLEVEL	43
+#define EDITLEVEL	44
 
 #define COPYRIGHT_BANNER_A \
 "NetHack, Copyright 1985-2009"

include/rm.h

@@ -376,6 +376,9 @@ extern struct symsetentry symset[NUM_GRAPHICS];		  /* from drawing.c */
  * The structure describing a coordinate position.
  * Before adding fields, remember that this will significantly affect
  * the size of temporary files and save files.
+ *
+ * Also remember that the run-length encoding for some ports in save.c
+ * must be updated to consider the field.
  */
 struct rm {
 	int glyph;		/* what the hero thinks is there */
@@ -389,11 +392,6 @@ struct rm {
 	Bitfield(roomno,6);	/* room # for special rooms */
 	Bitfield(edge,1);	/* marks boundaries for special rooms*/
 	Bitfield(candig,1);	/* Exception to Can_dig_down; was a trapdoor */
-
-#ifdef DUNGEON_OVERVIEW
-	Bitfield(styp, 6);	/* last seen/touched dungeon typ */
-	/* 2 free bits */
-#endif /* DUNGEON_OVERVIEW */
 };
 
 /*
@@ -541,6 +539,10 @@ typedef struct
 }
 dlevel_t;
 
+#ifdef DUNGEON_OVERVIEW
+extern schar lastseentyp[COLNO][ROWNO];	/* last seen/touched dungeon typ */
+#endif /* DUNGEON_OVERVIEW */
+
 extern dlevel_t level;	/* structure describing the current level */
 
 /*