Header cleanup in Qt4ProjectManager.

Disentangle the covariant returns and introduce
convenience accessors.
Move internal classes away from Qt4Project.

Change-Id: I6c3158988824d2a159b1b3f8ecdf8432c32be2bc
Reviewed-on: http://codereview.qt.nokia.com/3216
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

src/plugins/qt4projectmanager/makestep.cpp

@@ -35,6 +35,7 @@
 
 #include "qt4project.h"
 #include "qt4target.h"
+#include "qt4nodes.h"
 #include "qt4buildconfiguration.h"
 #include "qt4projectmanagerconstants.h"
 
@@ -222,7 +223,7 @@ bool MakeStep::init()
 
 void MakeStep::run(QFutureInterface<bool> & fi)
 {
-    if (qt4BuildConfiguration()->qt4Target()->qt4Project()->rootProjectNode()->projectType() == ScriptTemplate) {
+    if (qt4BuildConfiguration()->qt4Target()->qt4Project()->rootQt4ProjectNode()->projectType() == ScriptTemplate) {
         fi.reportResult(true);
         return;
     }