Extension methods required for the IElement interface

The following points outlines the use of the dimensional interfaces as well as extension methods required to be implemented by them for them to function correctly in the Spatial_Engine methods.

Please note that for classes that implement any of the following analytical interfaces, an default implementation already exists in the Analytical_Engine and for those classes an implementation is only needed if any extra action needs to be taken for that particular case. The analytical interfaces with default support are:

Analytical Interface	Dimensional interface implemented
`INode`	`IElement0D`
`ILink<TNode>`	`IElement1D`
`IEdge`	`IElement1D`
`IOpening<TEdge>`	`IElement2D`
`IPanel<TEdge, TOpening>`	`IElement2D`

Please note that the default implementations do not cover the mass interface IElementM.

If the BHoM class implements an IElement interface corresponding with its geometrical representation:

Interface	Implementing classes
`IElement0D`	Classes which can be represented by `Point` (e.g. nodes)
`IElement1D`	Classes which can be represented by `ICurve` (e.g. bars)
`IElement2D`	Classes which can be represented by a planar set of closed `ICurves` (e.g. planar building panels)
`IElementM`	Classes which is containing matter in the form of a material and a volume

It needs to have the following methods implemented in it's oM-specific Engine:

Interface	Required methods	Optional methods	When
`IElement0D`	`Geometry()` `SetGeometry(Point point)` `HasMergeablePropertiesWith(IElement0D)`
`IElement1D`	`Geometry()` `SetGeometry(ICurve curve)` `HasMergeablePropertiesWith(IElement1D)`	`Elements0D()` `SetElements0D(` `List<IElement0D> newElements0D)` `NewElement0D(Point point)`	`IElement1D` which endpoints are defined by `IElement0D`
`IElement2D`	`OutlineElements1D()` `SetOutlineElements1D(` `List<IElement1D> outlineElements1D)` `HasMergeablePropertiesWith(IElement2D)`	`InternalElements2D()` `NewInternalElement2D()` `SetInternalElements2D(` `List<IElement2D> internalElements2D)`	If the `IElement2D` has internal elements

`IElementM`	`MaterialComposition()` `SolidVolume()` or `VolumetricMaterialTakeoff()`

Spatial_Engine contains a default Transform method for all IElementXDs. This implementation only covers the transformation of the base geometry, and does not handle any additional parameters, such as local orientations of the element. For an object that contains this additional layer of information, a object specific Transform method must be implemented.

This is checked by this CI check so any changes to the requirements should be reflected in the check appropriately.