cpp/locale/wstring convert/wstring convert

@1@ Default constructor. @2@ Constructs the object with a specified conversion facet, using default-constructed values for the shift state and the error strings @3@ Constructs the object with a specified conversion facet and specified shift state, using default-constructed values for the error strings @4@ Constructs the object with specified error strings, using  as the conversion facet and the default-constructed  as shift state. @5@ The copy constructor is deleted, wstring_convert is not