pyVmomi should never extend base or core types

This VmomiSupport.py#L179 is considered extremely bad form in the Python community. Extension of core types ties the code to interpreter internals that may not be intended for exposure. This is akin to using a hidden API and should be avoided or at least isolated so that potential damage is easier to control.

Rewrite the code so that the class Link is not needed anymore or so that Link can operate without directly extending a core type.