Fixed some bugs, added Polar emitter type (lets you move things in circle/pretzel shapes or along a radius, or both), tweaked Helix emitter type, added emitter parameters to randomise the zoom (x/y/both) of emitted sprites.
Faster movement of something in the canvas (with WASD) or the selected row/keyframe in the timeline (with left/right/up/down) now happens when holding Ctrl rather than Shift. Fixed visual error when undoing/redoing.