Create a ComplexTraversalTest with crazy nested gnarly traversals.

Our ProcessSuite has numerous tests verifying the semantics of the various steps. Unfortunately, these tests are on simple traversals focused on exposing the step in question in isolation.

It would be good to add ComplexTraversalTest to the ProcessSuite which has traversals over the Grateful Dead graph (for complexity reasons) doing:

1. Numerous nests.
2. Match/Select/Where complexities.
3. Global side-effect access and unrolling and injecting.
4. ... just a bunch of nasty stuff.

This will give us much more confidence as we add more strategies and potentially, mess up our algebra which isn't exposed by the simple "flat'-traversals we current test with.

dkuppitz — would you be interested in doing this?