0028934: Coding - Eliminate compiler warnings in OCCT samples

- covering Qt warnings for compilation under MSVC 2013 and greater
- avoid warning about 'M_PI'(and others) redefinition warning of math.h: includes of QtWidgets should follow after other includes.

samples/qt/Tutorial/src/ApplicationTut.cxx

@@ -3,9 +3,11 @@
 
 #include <OSD_Environment.hxx>
 
+#include <Standard_WarningsDisable.hxx>
 #include <QFileDialog>
 #include <QStatusBar>
 #include <QMdiSubWindow>
+#include <Standard_WarningsRestore.hxx>
 
 ApplicationTut::ApplicationTut()
     : ApplicationCommonWindow( )

samples/qt/Tutorial/src/DocumentTut.cxx

@@ -1,8 +1,10 @@
 #include "DocumentTut.h"
 
+#include <Standard_WarningsDisable.hxx>
 #include <QFileDialog>
 #include <QMessageBox>
 #include <QApplication>
+#include <Standard_WarningsRestore.hxx>
 
 #include <TopoDS_Shape.hxx>
 #include <AIS_Shape.hxx>

samples/qt/Tutorial/src/Main.cxx

@@ -2,8 +2,10 @@
 
 #include <OSD_Environment.hxx>
 
+#include <Standard_WarningsDisable.hxx>
 #include <QApplication>
 #include <QTranslator>
+#include <Standard_WarningsRestore.hxx>
 
 int main ( int argc, char* argv[] )
 {