removed last append statement from csr_to_col
removed last append statement from csr_to_col

zasdfgbnm/qutip,qutip/qutip,cgranade/qutip,zasdfgbnm/qutip,cgranade/qutip,qutip/qutip,anubhavvardhan/qutip,anubhavvardhan/qutip