Code Refactoring

Took a shot at some refactoring.

- Removed excessive `.lower()`s in `check_term()`
- Rewrote `deal()` to use a for loop rather than a counter-based while loop
- In instances where `if type(terms) != list` was used, converted the single integer/string to a list containing that one value to reduce redundancy
- Clarified joker-based return values