build A | 4/27 update: item system, level refactor

today's update includes the following:

• the OC entity in level 0 has been removed
• environmental lights has been changed, and ceiling lights no longer clip through the ceiling 
• inventory system has been implemented
• various physical items has been added, and general UI elements (such as health and level information) has been moved to "smart watch" item
• crates will now randomly disappear/reappear
• compass now doesn't work propriety in level 0 (intentional)
• levels has been refactored based on wikidot backrooms article. 
• level progression now relays on exit landmarks.
• overall prefab optimizations/minor bug fixes

and that's all. I'm still open to feedbacks/requests. feel free to let me know...