Added conversation engine

-Can now start conversations with characters (if defined)
-Conversations are branching, and can be quite deep
-Added requirements for certain conversation branches, which are basically checks to see if the player has
  a certain item, or a skill high enough. If the check(s there can be multiple requirements) pass, the choice
  is shown
-Added in two simple conversation trees for the barkeep and the cloaked figure to test it out