New space objects / remove pivots

Background

Space objects are different classes that use polymorhism to create different types of functionality. This also includes some abstract classes (ArtificialBody and SpaceObjectVessel), which only exist to allow common functionality for subclasses.

A problem with the current system is that all SpaceObjectTransferable types need a pivot to exist outside of a ship. This is because they have certain features that ArtificialBodies do not have, such as gravity and room triggers.

Proposal

Remove the existing space object classes and implement a new system based on composition.

With composition we create interfaces space objects can extent to allow them to do the functionality we want. The benefit with this is that we only need to implement the features the object needs, while avoiding creating a web of categories (abstract classes) to group related classes together.

Adding space station as its own space object (is currently a web of ships docked together) and removing parents has a big benefit in that it no longer requires a destinction between parent, anchor and main vessel id.

• Implement space stations as a space object type.
• Remove parent as a concept.
• Remove pivots.

Additional context

Read the documentation on the website https://openhellion.github.io/documentation/space-objects

Start by reading the space-object documentation at https://openhellion.github.io/documentation/space-objects and comparing it with the current client hierarchy. Map the existing space-object, parent, anchor, main-vessel, and pivot concepts before changing them. Done means space stations are space-object types and all three listed concepts are removed.