Addresses two sources of inconsistency in the output of enumpoly:

[tturocy]

1. In the polynomial system solver, checks whether perturbations attempting to move off of a singular point are successful, rather than failing silently.
2. Make the iterator over sequences iterate sequences in a deterministic order.

[tturocy]

@rahulsavani We can put this on our agenda for the next meeting, specifically w/r/t whether we want to do anything else with the tests for this method.