qdbusxml2cpp should avoid to generate cpp language-specific keywords

When the XML file contains a methods or properties, called similar to the cpp keywords, e.g. like "Class", then the qdbusxml2cpp generates a files which contains a variable names like "class", that confusing the cpp compiler.

For example, the input XML file contains following:

    <property name="Class" type="u" access="read"></property>

then the generated output header will be contains following:

    Q_PROPERTY(uint Class READ class)
    inline uint class() const
    { return qvariant_cast< uint >(property("Class")); }

as you can see, there are two keywords "class".  So, resulting property need to change something like to:

    Q_PROPERTY(uint Class READ classProperty)
    inline uint classProperty() const
    { return qvariant_cast< uint >(property("Class")); }

Otherwise it is impossible to use the qmake's features like: DBUS_INTERFACES and DBUS_ADAPTORS.