ServerManagerCore: Replace vtkPVXMLElement with pugi::xml_*
ProxyDefinitionManager
keeps a separate std::shared_ptr<pugi::xml_document>
per proxy definition. When one is updated is simply creates a new one.
The Proxy is given the std::shared_ptr<pugi::xml_document>
upon construction
and is kept internally.
Resolves #6 (closed)
Edited by Christos Tsolakis