SF patch 536615: travel cache

This is derived from the proposed patch and feedback to it.  This applies
the last-position cache behavior without an option, making the behavior
more like it is for interfaces with a mouse, where holding the mouse still
acts the same way as the travel cache.  The code is not #ifdef'd either.

doc/fixes34.2

@@ -96,6 +96,7 @@ when jousting a pudding into a polymorh trap, it was possible to end up
 don't allow polymorphed player to web over the stairs
 geographical shopkeeper updates
 stethoscope use should be free the first time it's use per player move
+travel command caches last position to make non-mouse less painful
 
 
 Platform- and/or Interface-Specific Fixes

include/flag.h

@@ -176,7 +176,8 @@ struct instance_flags {
 	int      purge_monsters;	/* # of dead monsters still on fmon list */
 	int *opt_booldup;	/* for duplication of boolean opts in config file */
 	int *opt_compdup;	/* for duplication of compound opts in config file */
-	uchar bouldersym;		/* symbol for boulder display */
+	uchar	bouldersym;	/* symbol for boulder display */
+	coord	travelcc;	/* coordinates for travel_cache */
 #ifdef WIZARD
 	boolean  sanity_check;	/* run sanity checks */
 	boolean  mon_polycontrol;	/* debug: control monster polymorphs */

src/cmd.c

@@ -2413,15 +2413,20 @@ dotravel()
 
 	if (!flags.travelcmd) return 0;
 	cmd[1]=0;
-	cc.x = u.ux;
-	cc.y = u.uy;
+	cc.x = iflags.travelcc.x;
+	cc.y = iflags.travelcc.y;
+	if (cc.x == -1 && cc.y == -1) {
+	    /* No cached destination, start attempt from current position */
+	    cc.x = u.ux;
+	    cc.y = u.uy;
+	}
 	pline("Where do you want to travel to?");
 	if (getpos(&cc, TRUE, "the desired destination") < 0) {
 		/* user pressed ESC */
 		return 0;
 	}
-	u.tx = cc.x;
-	u.ty = cc.y;
+	iflags.travelcc.x = u.tx = cc.x;
+	iflags.travelcc.y = u.ty = cc.y;
 	cmd[0] = CMD_TRAVEL;
 	readchar_queue = cmd;
 	return 0;

src/hack.c

@@ -768,6 +768,7 @@ boolean guess;
 				    nomul(0);
 				    /* reset run so domove run checks work */
 				    flags.run = 8;
+				    iflags.travelcc.x = iflags.travelcc.y = -1;
 				}
 				return TRUE;
 			    }

src/options.c

@@ -516,6 +516,7 @@ initoptions()
 	for (i = 0; i < WARNCOUNT; i++)
 		warnsyms[i] = def_warnsyms[i].sym;
 	iflags.bouldersym = 0;
+	iflags.travelcc.x = iflags.travelcc.y = -1;
 	flags.warnlevel = 1;
 	flags.warntype = 0L;