TGenCollectionProxy
Proxy around an arbitrary container, which implements basic
functionality and iteration. The purpose of this implementation
is to shield any generated dictionary implementation from the
underlying streamer/proxy implementation and only expose
the creation functions.
In particular this is used to implement splitting and abstract
element access of any container. Access to compiled code is necessary
to implement the abstract iteration sequence and functionality like
size(), clear(), resize(). resize() may be a void operation.