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'd rephrase this as "takes one optional argument."