Prediction for 0.8

[TsFreddie]

I'm glad that prediction for other players is now official, and it is no doubt a highly demanded feature. Since the PR is now closed, I would suggest keeping a discussion regarding a future version of prediction.

Here's the future works stated in the PR:

• [ ] Predict actions on other tees
  • Currently when you hammer another tee with cl_predict_players on, the force on the other tee isn't predicted
• [ ] Predict grenade jumps
• [ ] Projectile prediction (for grenade, shotgun, pistol)

[TsFreddie]

While I'm at it. Here's my thought:

• Entities prediction is obviously the key of "finishing up" the feature. And making entities as part of shared code should be a feasible idea. https://github.com/teeworlds/teeworlds/pull/2650#issuecomment-641176204
• In turns, we need a way to let server and client to communicate which entities are "standard" and could be predicted.
• I would imagine entities should be good enough™ for most mods to use without modification, therefore, allowing the prediction to be enabled in most cases.
  • I think we could use more tunning params including but not limited to:
  • The hammer force which is not standard in the popular fng gametype.
  • Ammo regen and reload time/fire delay.
  • We should section tunning params into "categories" and in the case of non-standard entities are used, server should be able to opt-out some but not all types of prediction based on which "category" they decided to abandon all together.
  • And of course, we need better ways to send tunning params before any of these are implemented.
• There are the types of games that uses entities for absolutely everything and behave drastically differently even among the same type of entity, like InfClass or any "city" types of game.
  • Bundle tuning params to each entity is obviously a bad idea. But sometimes, these gametypes still use standard guns along with other crazy wild entities. I think it might be a good idea to allow server to turn off prediction on a per entities basis.
  • Or, we flat out turn off all entities predictions that are not created by a prediction (e.g. the character entities predicts a grenade to be fired, then only that grenade's prediction is turned on, if the server did not opt-out grenade prediction)