function-args.el (moo-navigate-members): new function.
function-args.el (moo-handle-completion): insert tag for single candidate.
function-args.el (moo-propose-virtual): refresh cache when called with arg.
function-args.el (moo-propose): list completions for current class members.

* (moo-propose-override): complete all functions
* (moo-propose-virtual): complete only virtual functions
* (moo-propose-variables): complete only variables - maybe useful just for info.