Type ParamMeta

          object --+            
                   |            
                type --+        
                       |        
         sip.wrappertype --+    
                           |    
PyQt4.QtCore.pyqtWrapperType --+
                               |
                              ParamMeta

This metaclass modifies the creation of AbstractCompoundParam instances in
the following ways:

    1) Stores the names of subparams on the subparam descriptor object. For
    example:

        class Coord(AbstractCompoundParam):
            x = IntParam()
            y = IntParam()

    In this example, the descriptor x.param_name == 'x'.

    2) A signal is dynamically added to the compound param for each
    subparam. The signal is names <subparam-name>Changed. (ex.
    coord.xChanged and coord.yChanged). This way, subclasses of
    AbstractCompoundParam do not need to explicitly define signals for each
    subparam.