updated fixed SINGULAR parts in branch "vanishing-ideal"

git-svn-id: http://www.singular.uni-kl.de/svn/branches/Singular-vanishing-ideal@12575 2c84dea3-7e68-4137-9b89-c4e89433aadc
Updating vanishing ideal stuff
Fixed unchecked end()s of std::list<>, mixed primes and exponents