Added Happy Mask Salesman + Trading Sequence

- Added 7 more masks
- Utils for timed chat messages and item granting
- Complete Mask trading sequence, requiring player to borrow a mask,
sell it, bring the money back, etc.
- Completing the trading sequence opens up the Happy Mask Shop for
business, allowing player to borrow a mask at a time
- Added Happy Mask Salesman: rename a villager to Mask Salesman, then
interact to turn them into the salesman
- Interacting with villagers while wearing a mask elicits a variety of
responses based on the mask and villager profession