save and load no-physics sprites
print exception when level fails to load
dont crash when creating box (due to no idea od do_physics param)
basic support for using splines to create polygons
prevent touch motion events being sent to game when touch started in menu
can remove spline points
set spline menu names better
set tool to edit after creating spline
use smoothness slider value on spline creation
remove debug statements
edit and delete spine points respects camera zoom
convert polys to splines on edit, delete splines correctly