refactor to allow word index tests to be reused with new IWordIndex implementation + add a new (failing) test case
Added a fancier, faster implementation of the word index. It currently has the same bug with multi-character tiles as the simple implementation.

Some refactoring and cleanup is needed
Added a benchmark project to measure speed differences between various implementations.

FancyWord Index is 32x faster to initialize and 7.8x faster to find moves than SimpleWordIndex
Added a slightly less fancy WordIndex implementation which, contrary to its name, significantly outperforms the fancy implementation when calculating available moves.
Added an ugly but functional gui