Generic object referencing in the InstanceHierarchy

[LeonHanke]

During the introduction of the new class section Sequence and ContextHiding, we got reminded that we have to adapt our code every time a new section and structure for objects is created, because there is no direct indication of which objects of a class must be instantiated in which structural "folder" in the InstanceHierarchy.

One solution could be, that the objects of the StructureClassLibrary get a new attribute that indicates the SystemUnitClassLib section of the object they will contain.

e.g.
Object: StructureClassLibrary/DeviceStructure
New attribute "ObjectClassReference": DeviceClassLibrary/Device

[AlexTxen]

Supporting documentation for AML library is to be created and stored in this repository. It should cover similar topics on library usage.
Adding additional attributes to library itself seems redundant.

[cdenisey]

See #52