Dynamic classes

The dynamic classes are implemented as per above:

• class table: the class descriptor is just an attribute indexed (type, RA, RA_Δ, etc.) array with indexes pointing out to the relative offset of the attribute in question.
• all the attributes within the class table, their names and numbers, must either be hard-coded or loaded to be known at the time when the class arrays are allocated, since each class array must be indexed by all known attributes,
• object layout: objects are allocated to contain exactly what the class array allows, and just nothing more ¹).

¹)	with the natural exception for pointers to memchunks representing objects in a quite different way