Bots that play the objective

Bots in Shoot and Destroy are ordinary players to the server, named Bot_ plus a generated name. This update teaches them to actually play:

• they plan their way to the objective: digging, bridging, swimming out
• they take cover behind whatever is there
• they hear digging and react to being shot
• CTF roles: a defender behind a camouflaged wall, an infiltrator tunnelling with a bodyguard, rushers and attackers
• squads in CTF, and the score always in sight

Difficulty is easy, normal or hard, set in the config or from the in-game menu.