New player movement physics

Updated locations:

• Central street location

• Location with a flying platform and a room with a green key

Fixed bugs:

• Door opening script not working when picking up the first shotgun

• Fixed lighting bugs in the green key location

I am gradually updating the new demo. Here's what has been done in this update::

• 20% of the locations have been changed, essentially recreated, with new traps, textures, etc.

• Fixed bugs in the location with the green key lift, now the light and shadows are displayed correctly, and the platform with the key lowers once (previously it returned to the top, making it impossible to lift the key)

• Улучшена оптимизация в ущелье с лавой(не до конца, но больше нет огромных просадок fps)