enumeration support for the wrapping of ParameterObject

[romangrothausmann]

It would be helpful to have a way of enumerating a list/dict of a ParameterObject like for i, parameterMap in enumerate(parameterObject):. Currently, this needs to be done as:

    for i in range(parameterObject.GetNumberOfParameterMaps()):
       parameterMap = parameterObject.GetParameterMap(i)