Adds the ability to load more then one IClientNetworkServer thereby allowing additional client network servers at the same time.   Use comma separated values in clientstack_plugin in your config.   Additional plugins lying around shouldn't be picked up because the loader only loads configured dll assemblies and breaks at the first IClientNetworkServer found in the assembly.  (the only new functionality is the ability to specify more in config).   Note: The existing functionality also passes in a nini config..   and has a boolean to determine if the client network server should be initialized for a specific scene.
Merge branch 'master' of ssh://opensim/var/git/opensim