Slaughterhouse b3a

• merged models together to increase performance
• moved hud assets to "vgui/replay/thumbnails" directory to avoid sv_pure conflicts
• misc modernizations

the base map/layout is pretty bad and i don't really intend to touch the layout as-is. others can feel free to look at it and learn why boxy maps are a bad idea lol

pd_slaughterhouse_b2 has been released. Here are the notable changes:

- Fixed a memory leak caused by missing sounds
- Added the meat grinder to the lowest level of the store
- Added wood pillars to the store's interior
- Adjusted store shelves
- Fixed the grinder's door