v0.2.0

Internal changes to make module distributable

- The triangle library is now built directly into every target instead
  of included as a shared library. This would lead to longer build times
  but each worker only builds one target, so it has no CI/CD impact.

- The C++ standard API for std::optional is not fully implemented on all
  macOS systems. Importantly, the `value()` method is marked as
  unavailable. Thankfully we can sidestep the problem by dereferncing
  the optional value or using pointer semantics such that `opt.value()`
  becomes `*opt` and `opt.value().method()` becomes `opt->method()`.
  These changes should not effect the Python interface.