Set resolveProxies=true for remaining cross-file references

Some references intended to be cross-file by the spec did not
have resolveProxies set (ConversationLink.source/targetRef, 
FlowElement.categoryValueRef).

Their opposite references had to be removed due to requirements 
by EMF and will have to be implemented manually later. This 
concerns InteractionNode.incoming/outgoingConversationLinks
(implemented in subclasses) and 
CategoryValue.categorizedFlowElements.

See discussion on mailing list from 19th August.
14 files changed