Moved code from Global.gd and Canvas.gd to DrawingAlgos.gd. Will also move the fill_gaps and draw_brush methods of Canvas.gd next. Maybe even refactor the inside of them a bit to make them easier to read.
Removed separators entirely. Also made the AnimationTimeline have a StyleBoxFlat of its own, which we use to expand its margin top to cover the little space left because of the VSplitContainer. We also use a TextureRect as a fake VSplitContainer grabber.