allows overload of "=" to clone mlist with pointer
Reported by Allan CORNET
It is a general trouble when we manages mlist with a pointer as element
Here example with xml module:
dA = 3
dB = 3
clear dA
dB
docA = xmlDocument("TMPDIR/foo.xml")
docB = docA //
xmlClose(docA)
clear docA
docB
docB =
!--error 999
%XMLDoc_p: XML object does not exist.
I waited that docB exists again
docB is only a alias on previous docA