Handle exits gracefully

Handle exiting the bot more gracefully:

• Catch SIGINT, SIGTERM, and SIGKILL (if possible) - see #76 (closed)
• Have top-level try-catch, or targeted try-catch around inputs, processors, and outputs
• Flush any pending data saves - add proper disposes to all adapters, processors, managers, etc:
  • World data persist: IWorldManager - see #76 (closed)
  • Any state saves for input adapters: particularly, FileInputAdapter, for file position - see #77