`AbstractShape` parameter unnecessary for `AbstractObject`?

[StackEnjoyer]

Currently, a major building block of the API is defined as

abstract type AbstractObject{T <: Real, S <: AbstractShape{T}} end

This is a legacy of the early days. In the mean time, SingleShape and MultiShape types have been introduced, making the AbstractShape parameter meaningless. I recommend we get rid of it. There are currently no functions in BMO that use this parameter for dispatch anyways. This will be a breaking change ofc for all users that implement some form of <: AbstractObject.

[StackEnjoyer]

Revision required for the following types:

• AbstractObjectGroup
• IntersectableObject
• AbstractRefractiveOptic
• AbstractReflectiveOptic
• NonInteractableObject
• AbstractBeamsplitter
• AbstractPlateBeamsplitter
• AbstractDetector
• AbstractJonesPolarizer

[StackEnjoyer]

Fixed with 476c882