Bugfixes and refinement of the bidi implementation (with API change,
requiring a major version bump). Also started the rework of the LUT
generation, which however is not used in the library code.

There is some work left to do regarding some of the Unicode algorithms,
but overall libgrapheme is pretty solid at this point.

Bump version to 3.0.0

We need a major bump as the bidirectional API changed since the last
release.

There need to be some refinements to some of the implementations for
conformance, but overall it works reliably.

Signed-off-by: Laslo Hunhold <dev@frign.de>