remove prescient travel command behavior

Addresses reports R718, R772.1, <Someone> P's extra move bug
- when there is a previously seen path or a straight path, always take it
- incorporate fix to ensure no extra "." turn at the end of traveling, but
 still avoid stepping into traps/pools, et al
- include a general "G"-command (and travel) fix to avoid stepping in
 known pools/lava while blind
- when there is no such path, "guess" at a path by finding an intermediate
 location that the hero couldsee that is closest to the actual goal, the
 intermediate goal is re-determined at each step
- when Blind, don't use couldsee for determining straight paths, just direction
- do not consider doors or most boulders obstacles for picking travel
 paths, test_move has a new mode to differentiate this case from the regular
 test case
- don't include known trap locations in the travel path, avoids unnecessary
 stops along the way, and usually doesn't affect the path length
- reformatted the code a bit so I could follow it

include/hack.h

@@ -178,6 +178,11 @@ NEARDATA extern coord bhitpos;	/* place where throw or zap hits or stops */
 /* Flags to control dotrap() in trap.c */
 #define NOWEBMSG	0x01	/* suppress stumble into web message */
 
+/* Flags to control test_move in hack.c */
+#define DO_MOVE		0	/* really doing the move */
+#define TEST_MOVE	1	/* test a normal move (move there next) */
+#define TEST_TRAV	2	/* test a future travel location */
+
 /*** some utility macros ***/
 #define yn(query) yn_function(query,ynchars, 'n')
 #define ynq(query) yn_function(query,ynqchars, 'q')