Letter distribution chart

[JoshuaFox]

This creates a chart as follows:

• This is the first added feature, in contrast to a bug fix. So, it deserves more caution.
• As requested, this does not alter board size. Also, in a typical browser, the right area was just wood-texture background, so this fits well.
• The server adds the letter distributions to the game data it sends.
• In rendering the board, this distribution received in gameData is used to build the chart on the right.
• The CSS is adjusted minimally to get a stable appearance. If there are design considerations, please let me know or tweak this.