Effort to cleanly define interface for the camera_observer class
these are incomplete updates, but I want to merge with master, and work
from there, I'm still confused about how to use git.
Getting ready to remove ceres_excal.hpp since it now has no code
Not sure why git won't let me switch branches, so I'm trying to commit first
Perhaps I need to add all the modified files first?
All my latest changes which represent both improvements in data structures, and also in compliance to coding style.
Completed set of data structures ready for review.