guard against later change of behaviour of ordering generators in output of groebner

[jakobkroeker]

in 'algeDeco_i'

ideal K;
for(j=1;j<=sizepr;j++)
{
K=groebner(pr[j]);
 if (size(K)>1)
{
             K = K[2..size(K)];
     }

Anne:

maybe put a guard against later change of behaviour of ordering generators in output of groebner:
if(nselect(ideal(K[1]),1..n)[1] != K[1]) // checks that no variables occur in K[1]
{
ERROR("Internal behaviour of ordering of generators in groebner has changed.
This code does not comply to the new behaviour please inform the authors.");
}