makefile: Build with $CC or cc
license: Include AGPLv3 license text
status: Return 0
subglyphs: use N and M for the other diamond corners
asc: No longer create bitmap layer

This works around scalable-font2's rounding issue,
where the bitmap layer is treated differently from the vector layer:

Subglyphs: Make corners of a circle using dbqp
structure: Change design of input format
ligatures: allow ligatures
txt2asc: Write id in format that sfnconv understands
tests: Commit failing tests
txt2asc: Correct glyph number
create asc file that can be parsed

Unfortunately, sfnconv mangles its dimensions from 20x20 to 24x17 🤦