Improve entity type confusion in the code base

[garsipal]

To reduce confusion and clearly differentiate between static and dynamic entities in the codebase, establish naming conventions for each type and their derivatives.

Static Entities

Static entities are map-based. These include models, decals, particles and item pickups that populate an environment.

Current references in the code:

• entity
• extentity
• gameentity
• server_entity
• gentities

Dynamic Entities

Dynamic entities include players, NPCs, movable props and projectiles.

Current references in the code (hierarchy):

• physent
  • dynent
    • gameent
      • monster
    • ProjEnt

Issue

Improve clarity and reduce ambiguity. Use a consistent prefix to separate static and dynamic entities?

Suggested names:

Static Entities

• entity -> MapProp
• extentity -> EditorProp
• gameentity -> GameProp
• server_entity -> ServerProp
• gentities -> GameProps

Dynamic Entities

• physent -> Entity
  • dynent -> Actor
    • gameent -> Player
      • monster -> Npc
    • ProjEnt -> Projectile