Draft of names, descriptions, stats, and costs for class-based equipment

Built out items.weapon, items.armor, items.head, items.shield per current design requirements hashed out on Trello at https://trello.com/c/L1H6LiZ3/110-character-stats-attributes-the-class-system . If we get sprite assets settled for dual-wield Rogues and staff+implement Mages, I'll revise this to match.