Debug view improvements, warp animation

* Add a visible frame one tile beyond the normal screen in debug mode.

* Fix the display of motion paths for mounted traps in debug mode.

* Add an animation for the warp trap.

game/settings.py

@@ -4,6 +4,10 @@
 TILE = 32                 # default tile size in pixels (levels may override)
 FPS = 60
 CAPTION = "Dying Phone"
+# Debug view only: how many extra tiles to reveal beyond the level on every side,
+# so off-screen geometry (e.g. an invisible catch-wall a step off the map) is
+# visible while designing. The true play area is outlined within this margin.
+DEBUG_VIEW_MARGIN = 1     # tiles of overscan shown around the level in debug
 
 # --- Physics (pixels / second, unless noted) ---------------------------------
 GRAVITY = 2200.0          # downward acceleration