* The F4 key to draw collision boxes works reliably again: it draws the
player's hitbox in world-space using the canvas.DrawStrokes()
function, rather than in screen-space so it follows the player
reliably.
* The F4 key also draws hitboxes for ALL other actors in the level:
buttons, enemies, doors, etc.
* The level geometry collision function is updated to respect a doodad's
declared Hitbox from their script, which may result in a smaller box
than their raw Canvas size. The result is tighter collision between
doodads, and Boy's sprite is rather narrow for its square Canvas so
collision on rightward geometry is tighter for the player character.
* Collision checks between actors also respect the actor's declared
hitboxes now, allowing for Boy to get even closer to a locked door
before being blocked.
* The colored locked doors and the Electric Door are increased in size
to better match Boy's sprite size.
* Colored doors now have a "locked" and "unlocked" state when closed;
when locked, a gold padlock hangs on the door with a keyhole shaped to
match the corresponding Colored Key.
* Added initial walking sprites for the player character, "Boy."
* Player doodad filename and title screen level are now configurable in
the balance/numbers.go package.
