Implements portal occlusion culling into Lethal Company to improve performance within the dungeon interiors of the game.

Build instructions:

1. Install Unity 2022.3.9f1.
2. Open the CullFactoryBurst project in Unity and build it to the CullFactoryBurst/Build directory, creating it if necessary.
3. Open the CullFactory project in Visual Studio and build it in Release.
4. All files that must be packaged with the mod will be present in the output directory.