use tuple for indexing in get_einsum_ops()
use tuple for indexing in get_einsum_ops()

BubuLK/sfepy,sfepy/sfepy,rc/sfepy,BubuLK/sfepy,vlukes/sfepy,sfepy/sfepy,BubuLK/sfepy,sfepy/sfepy,vlukes/sfepy,rc/sfepy,rc/sfepy,vlukes/sfepy