Rework monster decision code

[demoth]

Implement a composable monster ai decisioning using Behavior Trees

Character behaviors:

• idle states - fidget/stand
• react to damage - pain/dead state
• walking/running
• melee attack
• ranged attack
• TODO: "sliding"
• TODO: jump
• TODO: flying / swimming
• TODO: specials (medic)
• TODO: path target and combat target
• TODO: bosses

Priorities:

1. if triggered & has combat point -> go to combat point
2. if triggered & see enemy & fired at -> duck
3. if triggered & see enemy -> attack enemy
4. if triggered & !see enemy -> chase
5. if !triggered & has path-target -> goto path-target
6. else: Idle