Locks, Keys, Prompts and Cash.

-Added exclamation prompt when interaction is possible.
-Player speaks errors thrown by a failed interactions, ie "Not enough
money."
-Doors now have walls when closed, and can be opened after collecting
keys with the same door ID.
-Key to hub area dispensed after set amount of coins.
-Cash dispensed every n number of coins. Value of cash and the n
interval can be adjusted.
-Interact zones added to the hub vendor stores, awaiting a store menu
call.
-Speed gain per coin now scales with the coin's value.
-Refactored launch data to be a namespace with launch information, and
LevelProgress: an instance-based version of the previous LaunchData
class to handle changes in launch information as coin are gained.
-Rough key art.
-Full cash art.