Fix error : "Function passed by reference" in class CMS_poly_module_structure
Fix error : "assuming $this from incompatible context" in CMS_poly_module_structure
Method getSubFieldsDefinition rename in getSubFieldsDef

Because the function getSubFieldsDefinition in CMS_object_common is not
static and getSubFieldsDefinition in CMS_multi_poly_object is static
(CMS_multi_poly_object extends CMS_object_common)
Refactor calls of method CMS_multi_poly_object::getSubFieldsDefinition