Rubix-cube modelization library

As for now the library supports basic representation of a Rubix-cube The library is built for speed, most operations cost no allocations to perform. This does however mean that the library is NOT thread-safe and should be handled with the appropriate mutual-exclusion mechanisms to avoid memory corruption or unintended side-effects on a single cube.

The library supports the singmaster notation as a way to perform operations on a Rubix cube.

No solver is (yet) provided along with the library.