Fix segfault upon too much HarfBuzz concurrency.

Fix reentrancy complaints from GHC, attempt to fix segfault.

Add documentation & corrected type signatures.

Add, test, & fix shaping function.

Fix build linking errors (mostly by upgrading GHC).

I'm now running on this on elementary OS Jolnir.

Try wrapping HarfBuzz C++ functions in C functions for calling convention/linking issues.

Committing so I can try building on a newer OS.

Draft language bindings to font/face APIs.

Expose util functions on scripts & buffers.

Correction: buffer's codepoints are all Chars.

Reimplement parts of Harfbuzz where that's easier than writing a binding.

Removed a note where that turned out not to be the case.

Integrate guessing chars, document properties, expose default property values.

Implement conversion from functional Buffers to imperative Buffers.

Draft pure-functional Harfbuzz API.