Mixed index not used with "or-step"

[severinstampler]

A query like the following does not make use of the mixed index:
g.V().or(has('title', textContains('Trump')), has('name', textContains('Trump')))

In that example, I try to look up a search word in two different fields. I currently can't figure out how to correctly construct that query. A possible workaround would be to make a direct index query.

[pluradj]

duplicate of #163