fixed Sum in entry

in CommonHomalgTableForMAGMATools,
   CommonHomalgTableForMacaulay2Tools,
   CommonHomalgTableForGAPHomalgTools
secured gcd in CommonHomalgTableForMapleHomalgTools
assign external ring elements to external variables in CommonHomalgTableForMAGMATools

by suppressing "need_output" in
. Minus
. DivideByUnit
. Sum
. Product