Refactor the content classes.

They were needlessly class-based.
Move breeds back into levels.
Level pickers on dungeon test page.
Clean up area DSL.
More work on guide.
Temporary resistance to elements.
Split out actions into smaller libraries.
Give dogs a howl move that wakes nearby monsters.
Content content content!

- Add another level to the Goblin Stronghold
- Axes
- Slings
- Ash and yew bow prefixes
- Feng and Erlkonig quest monsters
- Cave bat, goblin ranger, sparkling slime, mischievous sprite, kobold priest, and saurian
Take moves into account when calculating experience.
Add IntelliJ project.
ran pub deps which updated dependencies
fixed missing getter