This is in preparation to move constraint off the GPU to simplify our
shaders, instead we only need to constrain once at raster time and never
again.
This also significantly reworks the freetype renderGlyph function to be
generally much cleaner and more straightforward.
This commit doesn't actually apply the constraints to anything yet, that
will be in following commits.
* font: disable default font features for Menlo and Monaco
Both of these fonts have a default ligature on "fi" which makes terminal
rendering super ugly. The easiest thing to do is special-case these
fonts and disable ligatures. It appears other terminals do the same
thing.
Not as straightforward as it sounds, but not hard either:
* Read OS/2 sfnt tables from TrueType fonts
* Calculate strikethrough position/thickness (prefer font-advertised if possible, calculate if not)
* Plumb the SGR code through the terminal state -- does not increase cell memory size
* Modify the shader to support it
The shaders are getting pretty nasty after this... there's tons of room for improvement. I chose to follow the existing shader style for this to keep it straightforward but will likely soon refactor the shaders.
