XSD-Schema: empty type `valueDataType_t` in IEC61360.xsd

The complexType: valueDataType_t in the IEC61360.xsd schema file is empty:

        <complexType name="valueDataType_t"/>

Therefore, it is impossible, to specify value data in accordance to the schema. Suggested Fix:

	<complexType name="valueDataType_t">
		<simpleContent>
			<extension base="anySimpleType"/>
		</simpleContent>
	</complexType>