Fixed a bug and tweaked the interface

Blanks now correctly dissappear from the player's tray after usage.
The popup asking for a letter to be used on a blank now displays letters in
alphabetical order.
Dictionary now loads in a separate thread

No progress bars, because after lovely three hours I hate them with fiery
passion.
OK won't be active until dictionary is loaded.
Merge pull request #33 from timorl/blank-fixes-and-tweaks

Fixed a bug and tweaked the interface
Merge pull request #34 from timorl/progress-bar

Dictionary now loads in a separate thread