Document shaping & version-number APIs!

Fix segfaults & include test assets (major refactor).

Finalize release 0.1!

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.

Draft pure-functional Harfbuzz API.