Method newOp

\brief Create a new placeholder op that will not replace an existing op An uninitialized placeholder for the new op is created. When (if) the new op is created it will not replace an existing op. The op that follows it must be given. \param numParams is the number of Varnode inputs intended for the new op \param opc is the opcode of the new op \param follow is the placeholder for the op that fol