Correctly named and categorized spawnmenu plants

Added cosmetic scenery

Added fully working plants

Added grass sway and env_wind

Added skybox, optimized grass meshes, fixed some collisions

Updated collisions and fixed shadows on some meshes

Added missing cave collisions

Completly reworked grass, fixed red turret collisions, refined inhib textures

Small bugfix

Replaced some placeholder models with new, added blue storekeeper