saving message history (trunk only)

On September 11, 2003 "<Someone>" wrote:
> When we're going to have a different save file format, could
> the last messages in the message history be saved as well, so
> ^P would work the same before and after saving (possibly
> including a few less messages to make room for the startup
> messages?).

This seemed like a reasonable request. This patch:
- adds the core support required.
- adds the tty supporting routines.

include/patchlevel.h

@@ -13,7 +13,7 @@
  * Incrementing EDITLEVEL can be used to force invalidation of old bones
  * and save files.
  */
-#define EDITLEVEL	3
+#define EDITLEVEL	4
 
 #define COPYRIGHT_BANNER_A \
 "NetHack, Copyright 1985-2003"