More comparisons

[dellaert]

Added

• Essential + K: uses new constructor to optimize for a single K
• "Binary + Ks" and "Binary + K": use EssentialMatrixFactor: makes error much less as only pairwise errors checked
  It's clear that the binary EssentialMatrixFactors do much better in terms of geodesic distance, even without "enforcing consistency". They also optimize quite fast. Although: I have to admit I don't understand how they can do better than "Calibrated", which uses ground truth K. Maybe the transfer error pushes away from ground truth in an unexpected way.

[travisdriver]

Looks great, excited to try out in GTSfM :)