Raw Stats not accessible until a Request

[caymansimpson]

A mon's stats are not accessible until a Request occurs, which makes it hard to make damage calcs without parsing and storing the team.

Would you be open to a PR that:

1. Tracks stats w/ an internal Pokemon._stats variable?
2. Updates the getter for Pokemon.stats, changing it from Pokemon._last_request to _stats variable?
3. Adds a setter for Pokemon.stats in Pokemon?
4. Updates internal _stats variable in Pokemon.update_from_request
5. In player._create_battle, calculates and sets the stats, with help from stats.py?