Feature: Add spirit_type to Spirits

[bitsoflogic]

Just like we have structure_type on the structures, I would like spirit_type on the spirits.

The idea here is to add Flow.js support for the global spirits value. Right now, I cannot create a proper union type because there's way to do disjoint unions:

// This says the keys are type SpiritId and the values are either type TriangleSpirit or type EnemySpirit
declare var spirits: { [SpiritId] : TriangleSpirit | EnemySpirit }


let spirit = spirits[0]
if (spirit.type === 'friend') {  // <========== I want to be able to do this

  // flow.js knows this is MyChosenSpirit, so it won't error when using its method:
  spirit.explode()

}

Keeping with the naming used in spirit.sight, I'd imagine that the type would be: 'friend' | 'enemy'

---

Flow.js isn't smart enough to filter based on a function like (spirit.id.substring(0, MY_USERNAME.length) === MY_USERNAME).

Possible workaround
As a workaround, I'm going to try adding the type every tick to all spirits (and not running that code through Flow.js)