Make rref test check that matrix is in rref
Make rref test check that matrix is in rref

jpflori/flint2,jpflori/flint2,fredrik-johansson/flint2,dsroche/flint2,jpflori/flint2,fredrik-johansson/flint2,dsroche/flint2,wbhart/flint2,dsroche/flint2,wbhart/flint2,fredrik-johansson/flint2,dsroche/flint2,wbhart/flint2,jpflori/flint2