starting to change slide_model to have the logic of changing slides

In order to make slide_object dumber and and not need to keep track of
slide info, we are moving the business logic to slide_model so that
the model can keep track of whether presentations are ready to switch
and don't need to run reveal_next or something.

src/main.cpp

@@ -102,7 +102,7 @@ int main(int argc, char *argv[])
   QScopedPointer<ObsModel> obsModel(new ObsModel);
   obsModel.get()->getObs();
   obsModel.get()->updateScenes();
-  slideobject.get()->setSlideModel(slideModel.get());
+  slideModel.get()->setSlideObject(slideobject.get());
 
   Settings *settings = new Settings;
   settings->setup();