Norns: additional screen commands, cairo glue

[tehn]

cairo has a crazy amount of drawing functions: see https://www.cairographics.org/tutorial/ https://www.cairographics.org/manual/index.html

currently only a few are brought out. some that should be added:

• [x] font selection (add roboto and aleph-font, select by index?)
• [x] font size
• [x] font alignment (we need right and center align) see cairo_font_extends
• [x] fill
• [x] draw rectangle
• [x] draw arc
• [x] draw curve
• [x] close path
• [x] draw circle (subset of draw arc, lua shortcut)
• [x] relative move to
• [x] relative line to

[tehn]

progress shot (and, the custom knobs/keycaps arrived!)

[tehn]

https://github.com/catfact/norns/pull/79