TD AI behaves differently than original

[giulianobelinassi]

In VanillaTD (and so does Remaster), the AI has some sense of "priority" that the original AI didn't have.

This is specially noticeable on enemy Airstrike. It will always try to target Artillery and Obelisks instead of always selecting the northeast unit, as in the original TD.

Although this makes the game more challenging, this has some strange behaviors in campaign. For instance, the Nod Mission 11 (Recover stealth tank technology) is insanely harder because of this behavior.