- add support for IDProp array slicing, but not resizing. - rename array attribute type to typecode and use chars 'f', 'd', 'i' which match pythons array module. (was using int's which only have a meaning internally). - rename function 'convert_to_pyobject' to 'to_dict' and 'to_list' for IDProp group and array types respectively. - remove 'len' array attribute, calling len(array) is fine.