Unit formations

[WestonVincze]

Implement unit formations

Create "clusters" of units that share a target, pathfinding, and formation

• determine the required distance between entities before they merge into a cluster
• allow for clusters to split if the closest target for all units in the cluster is not the same (i.e. there is more than one cluster in close proximity)
• each unit in a cluster will have an offset from the center of mass
• the cluster may need to track it's radius in order to navigate around buildings correctly
• a cluster will have a relative direction equal to its last non-zero velocity

Units will need to have cluster targets that will help a separate targeting system determine specific unit targets for each unit (unit 3 from cluster A targets unit 2 from cluster B)