[sv-cc] class defn, class var diagrams etc...

I looked at the problems related to classes. When I started looking at these
diagrams
and try to apply them to some examples, I found several problems.
 
For example, with the current diagrams,  type definitions were not
accessible from a class definition, virtual interfaces
which can be declared in classes were not accessible. For a language
definition of virtual interfaces, see 20.8 of P1800.
I found numerous issues which I attempt to fix here.
 
I would like to review this proposal which fixes several problems with
classes.
I think that it may take a while to discuss and understand this and I may
have to provide another version after
our discussion based on corrected interpretation.
 
Francoise
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