Bugfix: Fix screen wrapping, cleanup some log messages

Before this fix, you could go upwards and select the screen which
was at the rightmost because it also was the one topmost (if all
screen’s top position is equal).

include/xinerama.h

@@ -57,6 +57,6 @@ i3Screen *get_screen_containing(int x, int y);
  * This function always returns a screen.
  *
  */
-i3Screen *get_screen_most(direction_t direction);
+i3Screen *get_screen_most(direction_t direction, i3Screen *current);
 
 #endif