Outpost testbed.

contains: multi-layer material terrain, waterplane, wheeledvehicle, respawning AI turret, static mesh, particleemitternode(s), timeofday, forest, groundcover, postfx preset (edit: and a storm, physicszone, and decal and mesh road. sadly, no partidge in a pear tree)
dependencies:
#769 for groundcover material definitions, #771 to ensure water doesn't trap the player.