L4D map update

All basic map features on the top floor is complete. Focusing now on the bottom floor and main lobby. Spent a few days to design and detail the cafeteria and kitchen rooms.

- Elevator is now operational with sound effects.
- Redid the lobby floor texture to resemble a more professional office building tile floor.
- Finished the men and woman's bathrooms for the main lobby. Lighting still needs to be added.

Bugs:

- Lighting is piercing through cracks where the brushes connect in some areas of the map. Will go back to add lighting block brushes later on to correct this.