Added CalamaresUtilsGui
Added ProgressTreeModel/View, including different kinds of items.
Redone CalamaresWindow without UI file.
Const correctness in ViewStep and plugins.
No need to call expandAll from outside the model.
Enforce minimum size for main window.
Add getter for CalamaresWindow in CalamaresApplication.
Lots of model/view/delegate changes.
Created delegate for ProgressTreeView.
No more columns, only roles throughout the model.
Added row types and some user roles to the model.
Look and feel changes to ProgressTreeView.