* Add red fairies; tweaks to blue fairies and circles
* Add more fairies and a simple enemy archetype system
Note that existing stages not utilizing the new enemy spawning system
will have a visual regression - fairies will not have their magic
circles and particle effects visible. These are no longer implemented by
the enemy visual rules and require additional setup from the new spawner
wrappers. All stages should be converted to the new system.
Also improved old fairy sprites
* enemy_classes: rebalance HP
* enemy_classes: add EnemySpawner typedef
* items: add ITEMS() shortcut macro for use with enemy spawners
