Fix VBSP to use new property_parser options

- Also add parsing of StyleVar blocks, to import from BEE2 interface
-
Move bool_to_str into utils module

This way it's easier to use in other modules.
Add StyleVar to unlock Default Items

- This makes the entry/exit corridors and Primary Observation Room
deletable and copyable.
- AddGlobal will not run if the instance was already added into the map
- Conditions are evaluated ONLY in order - now we loop through all
instances once per condition instead of the other way around