more uniform init/exit model/view in session_manager, trading race wrt. session.phase for race wrt. global editor state;
more uniform init/exit model/view in session_manager, trading race wrt. session.phase for race wrt. global editor state;

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle