Write doctests
Don't load modules in GHCi

They get loaded automatically by "cabal repl". Adding them to GHCi's
configuration file just makes a bunch of warnings when you run "ghci".
Make the benchmarks do some real work
Remove type documentation

It wasn't really doing anything.
Update documentation
Rename "Board.rows" to "vectors"
Rename "Tile.value" to "number"
Add basic Game type