0.20.2

New Rest agent along with other fixes and changes.

• Observation spaces now require stocks to be in the last channel
• updated the example observation space to support this new requirement and to also contain player positional data
• implemented AltF4's puff bot from his tutorial video using the example action space
• redesigned is_defeated as a function decorator to reduce boilerplate code on new agents
• updated
• updated documentation in agents/README.md
• updated example file