Hangman: Some fixes/tweaks

-Possibly solving the issue with Android clients being able to guess an empty character.
-Adding a different command to end Event Games (to avoid Event games from being stopped by accident).
-Resetting the Event Timer when a game ends instead of when a game begins.
-Fixing games being started with less than 4 valid characters by using numbers.
Merge pull request #657 from IceKirby/patch-17

Hangman: Some fixes/tweaks