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

src/cmd.c

@@ -1977,7 +1977,7 @@ click_to_cmd(x, y, mod)
 
         dir = xytod(x, y);
 
-        if (!m_at(u.ux+x, u.uy+y) && !test_move(u.ux, u.uy, x, y, 1)) {
+	if (!m_at(u.ux+x, u.uy+y) && !test_move(u.ux, u.uy, x, y, TEST_MOVE)) {
             cmd[1] = (iflags.num_pad ? ndir[dir] : sdir[dir]);
             cmd[2] = 0;
             if (IS_DOOR(levl[u.ux+x][u.uy+y].typ)) {