Expose core classes for custom usage

[robhawkes]

Description

• The way I am using the CityJSON parser differs to the general implementation available within the core exports
• For example, CityJSONWorkerParser does a lot though I want more control and customisation over geometry generation
• Another example is to implement a parser into my own worker scripts (CityJSONWorkerParser tries to create its own worker)
• Or I may want to create an entirely different data management mechanism like streams, or worker pools
• Manually accessing ChunkParser has been helpful for me but it's not accessible via the root / index file

Expectation

• Expose all the useful classes from the parser in the root / index file (at least ChunkParser and GeometryParser)
• Core classes can be used to perform basic parsing so I can perform my own geometry processing or mesh / material application

[liberostelios]

Thanks for the remark! The plan is to have all classes available to the user so that they can use composition to enable whatever behaviour the want (or to extend the functionality). I was just lazy to do it so far, as I am still experimenting with things. 😇

Except for just exposing these files through the index, do you think there is a way that ChunkParser and GeometryParser can become more extensible? I am worried that these classes might be already a bit overloaded and could be decomposed even further.