keep gui as keyword option in Odeoptions for backward compatibility
keep gui as keyword option in Odeoptions for backward compatibility

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