added groundstate method to Qobj and switched eigenstates/ eigenenergies to sp_eigs
added groundstate method to Qobj and switched eigenstates/ eigenenergies to sp_eigs

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