Add support for TrueType Collection fonts

[wldevries]

Some fonts are shipped as True Type Collection font files (.ttc) in Windows, for example Microsoft JhenHei and Microsoft Yahei. It would be nice to be able to parse those as well. The format seems to be easy enough, it's just a header with TrueType fonts embedded.

https://docs.fileformat.com/font/ttc/

[roy-t]

It does look doable, but I haven't worked on this library in years and I was unaware that anybody was actually using it. I would welcome a contribution and I'd be happy to release a new version then. But I'm not sure if I can find the time to add support myself. :)