Add reasoning for why tag replacer needs callback.
Implement resourceUrl tag for resources.
Add getPluginServicesOfType to service registry API.
Rename getEndpointHtml to getEndpoint.
Add RPC providers and invoker implementation.
Add socket.io client plugin.
Add IO middleware providers, and implement RPC client.
Add test RPC provider and user.
Minor cleanups in RPC invoker and provider.
Minor style cleanups in script minifier.
Add docs to ResourceContext interface.
Make error messages for mismatched resource transformer better.
Add auth provider API plugin.