Qt4ProjectManager: Give a verbose tooltip on the Qt versions.

Reviewed-by: dt <qtc-committer@nokia.com>

src/plugins/qt4projectmanager/qtversionmanager.h

@@ -124,6 +124,9 @@ public:
     };
 
     QmakeBuildConfig defaultBuildConfig() const;
+
+    QString toHtml() const;
+
 private:
     static int getUniqueId();
     // Also used by QtOptionsPageWidget