CppEditor: Improve finding position for new includes

...by detecting include groups (separated by new lines, include types
and same dir prefix).

Task-number: QTCREATORBUG-9317
Change-Id: I73e80fdc715104901cb2d4f5b15b4cab5d04d305
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cpptools/cppmodelmanager.h

@@ -124,6 +124,12 @@ public:
         return m_includePaths;
     }
 
+    // Use this *only* for auto tests
+    void setIncludePaths(const QStringList &includePaths)
+    {
+        m_includePaths = includePaths;
+    }
+
     QStringList frameworkPaths()
     {
         ensureUpdated();