Usability improvements to titanium.query, more tests
Add gremlin-java dependency
Initial Gremlin Pipeline implementation

Only covers the most essential Pipes operations so far. To be fair,
many of them can be easier performed in Clojure via the usual collection
manipulation but Pipes makes it more efficient in cases with large
graphs, so support for more operations is coming in the future.
Don't refer to clojure.core/filter in this ns
Eliminate a few reflection warnings