Add basic music to game

**Is your feature request related to a problem? Please describe.**
Currently no music to play, which is a wasted opportunity to set atmosphere.

**Describe the solution you'd like**
Add overworld music, dungeon music, town music, etc.

You should hear town music get louder and louder as you approach it. Ambient music should almost morph into the town music. Maybe write everything in relative keys so it sounds good over eachother with minimal passing/neighboring notes to prevent atonal mess??

**Describe alternatives you've considered**
Describing music in text form, which will also come later, because you'll be able to compose.