Scenario 2 and 3 scaffolding

@BrettASwift @kadst43 Well on our way to being done with the scaffolding for levels 2 and 3. Level 2 is complete but missing some hint VO. Level 3 needs art (though maybe it's there? further down the canyon?) but has all necessary components (Blockly blocks and yamls). Known issues include some terrain in the way of the slope navigation, and a Blockly annoyance that requires closing the Blockly window after each scenario (If you leave the graph tab open it loses all of its blocks until you exit/re-enter).
I've removed the blackboard part since it wasn't needed and was an artifact from when I was trying to get the sensor to work. That's the part that required the blocks code be in the model but if you can think of a better way then we can work that out.