Consider adding some indirection around point drawing to speed up the TT2020 case

[ctrlcctrlv]

Drawing TT2020 glyphs is possible, but renders on my machine at only around 15FPS. Not as bad as FontForge's 0.33FPS, but not ideal.

I think it's mostly due to how many paths we're creating. (perf backs this theory up if I'm reading it right.) I think I can solve this with a little good old fashioned indirection, by drawing every point that will be the same color/stroke width in a single path.

15 FPS:

60+ FPS:

(Also, we probably shouldn't draw selected points twice, but this isn't as big a problem as creating thousands of Paths/Paints.)

Rust iterators should make this easier. Basically the current draw_point will just add a rect/triangle/circle to a one-per-render_frame struct, then we'll draw all the points with only four or five Paths/Paints.

This might be post-1.0 as it's premature optimization, but am writing it down so don't forget.

[MatthewBlanchard]

I'm going to look into batching the point/direction markers into a single path (well two with selected taken into account). This should improve performance for these types of cases.