fix argument wire start point
update image node to work with new interface
implement line node
implement quadratic curve node
implement bezier curve node
add method to draw arbitrary guide
draw supporting guides for curves' control points
move files around and rename categories in picker
use mixin getOutputAt method on all operators
implement sin and cos nodes
implement elapsed seconds node
restore background color after resize
update limit node
use mixins on map node
implement max, min and abs nodes