Implement CFF

[behdad]

It's a pain, but to implement hb-ot-font get_extents for CFF fonts, we need to implement pretty much all of CFF...

[KrasnayaPloshchad]

This may should be fixed along with CFF2 table.

[ebraminio]

Great that now we have #1113, shouldn't we merge that and add support for CFF's get_extents now that ot-font is used by default?

[ebraminio]

And of course it is another fuzzing hole :) Or maybe not as it is not used on shaping it self currently IIUC.

[behdad]

Great that now we have #1113, shouldn't we merge that and add support for CFF's get_extents now that ot-font is used by default?

Yes. Post-release.

[ebraminio]

As #1113