Combat AI hooks

[phobos2077]

Need to investigate the code, and think of some hook script ideas, that will allow to customize AI behavior.

Keep these possible goals in mind while searching for hook opportunities:

• Flanking AI
• Customize AI morale system without dirty hacks
• Playable cover system
• AI respecting new weapon types, like smoke grenades

[FakelsHub]

• [x] Need to implement a hook for the ai_best_weapon_ function.