New enemy AI needed

[DanielDees]

New enemy AI will be needed by the game.

Movement

AI will be added in the scripts/enemy_AI.js file.

1. Orbit (parent entity) : any enemy with this AI should orbit whichever parent entity it is sent.
2. Evade: enemy will move away from any player within its detection range while firing at nearest player until it has run outside of its detection range.
3. Orbit (player) : enemy with this AI will orbit the player that they are attacking.