minor changes to the 2nd floor and exterior

- started fitting out the second floor, three editing suites added
- mechanical, laundry and prop rooms added to the basement
- lowered the volume of the fire alarm
- changed the "silence" function of the fire alarm, the strobes will now continue to blink but the audio will be muted

lots more to add/finish!

Note: I am aware of an issue where the destruction of certain objects/areas (e.g. the gates/floor in the lobby) of the map causes the game to freeze for a few seconds. I've narrowed it down to one or more of the items in the external environment (e.g. the road, grass, road markings, parking bays etc), I still need to work out what object(s) are causing the spike in the time it takes for the destruction to occur.