Particle API

[JonatanWaern]

• Allow modification of particle definitions through script
• Creation of specific particles without using an emitter
• Query regions for particles and manipulate these once found (particularly would allow a zParticleKill trigger or similar)

[msg555]

Modification of particles can be done in a hacky way through vars and creating z_particle_trigger objects. A more direct particle API probably maekse sense.

Right now only the engine holds on to particle state, allowing particles to be created directly or queried would require an engine update.