Entity teams

[Katsutoshii]

Create a concept of team per entity.

• Have a Team enum per entity that needs one.
• In the Objective system, only allow friendly objectives to be set between same-team entities and allow aggressive actions like attacking only between units on different teams.
• Team enum:
  • Neutral
  • Red
  • Blue
  • ...
• Resource for tracking which team the player is playing as.