Trivia plugin: refactor Trivia object and values

Fix bug in the question/answer loop that would assign undefined to
either curQ, curA, or phase, preventing anyone from answering any
questions until this.curQs was empty, by changing all of the game
variables from global variables to Trivia properties. Created a
constructor for Trivia so its methods could be kept in its prototype
object to reduce property lookup times and later to allow me to refactor
parts of the commands that deal with these properties as prototype
methods.

Fix room.addRaw not updating chat.