Reduce include dependences in GUI; break cyclic dependence between View and Model

• renamed directories from plural to singular (Views->View, Utils->Util, etc etc)
• made GUI/Model independent of GUI/View
• organized GUI/Model into subdirectories
• moved GUI/main to App
• moved files from GUI/View to GUI/View/Toplevel
• broke most cyclic dependences between subdirectories of GUI/View (the remaining ones are mostly for calling functions from ProjectManager that should be moved down to ProjectDocument)
• obtained two subdirectories of GUI/Model with non-cyclic dependences (Component, IO); all other subdirectories still forming a big interdependent cluster
• removed some unused source files
• removed numerous unneeded includes
• corrected a few relative include paths
• splitted several source pairs into two pairs
• splitted class Application into two (ApplicationSettings vs SessionData)
• renamed many namespaces
• shuffled code in several functions to treat anomalous conditions first; no else after return
• substituted QWidget::parentWidget for m_mainWindow and other self-made solutions
• converted SavePlotAssistant from class to namespace
• moved some enum definitions to low-level file ID.h

GUI/View/Intensity/PlotStatusLabel.h

@@ -15,7 +15,7 @@
 #ifndef BORNAGAIN_GUI_VIEW_INTENSITY_PLOTSTATUSLABEL_H
 #define BORNAGAIN_GUI_VIEW_INTENSITY_PLOTSTATUSLABEL_H
 
-#include "GUI/Widget/Common/StatusLabel.h"
+#include "GUI/View/Intensity/StatusLabel.h"
 #include <QList>
 
 class ScientificPlot;