Silly PR. Some colliders added to cool demo
Merge pull request #661 from jtorrente/silly

Silly PR. Some colliders added to cool demo
Added ConversationSystem, DialogueSystem

- ConversationSystem processes a TalkComponent, which is added by
  TriggerConversation effects. They are display-independent.

- DialogueComponent processes DialogComponents, which can specify
  callbacks. Currently they all have the same style; this will
  be addressed in later commits.
Added ConversationDemo

Click on dialogues to choose / dismiss them.