Added update events for the command history model and workspace model. * history-dockwidget.cc: Moved string list model to dock widget. * octave-event-observer.h: Removed constness from accepted and rejected methods. * octave-event.h: Removed constness from accepted and rejected methods, add new event types. * octave-link: Almost removed all Qt code. * workspace-model: Moved update timer to model. * workspace-view: Model workspace model to widget.