Allow resting inside of walls in wizmode.

The change to abort a run command early if the target square is
uninhabitable (0.20-a0-387-gf587305) also affected resting, but that
broke the woken_rest test and probably others. Instead, check for
running as opposed to resting.

Also, don't abort the run command, but simply avoid the slime wall
message, if the target square can't be entered: this change restores the
"Why would you want to do that?" message when attempting to run into
water, lava, etc. when slime walls are not nearby.

crawl-ref/source/main.cc

@@ -1049,11 +1049,10 @@ static void _start_running(int dir, int mode)
     if (!i_feel_safe(true))
         return;
 
-    coord_def next_pos = you.pos() + Compass[dir];
-    if (!you.is_habitable_feat(grd(next_pos))) // only relevant for run
-        return; // don't warn about running through walls, etc
+    const coord_def next_pos = you.pos() + Compass[dir];
 
     if (!have_passive(passive_t::slime_wall_immune)
+        && (dir == RDIR_REST || you.is_habitable_feat(grd(next_pos)))
         && count_adjacent_slime_walls(next_pos))
     {
         if (dir == RDIR_REST)