- apply the pyflakes stick to strategies.py. In particular, try

- apply the pyflakes stick to strategies.py.  In particular, try
to get almost every method to be less than 50 lines.   For the relationship
loaders this meant finding some decent boundaries to split things up.
I find this style a bit unnatural as in some cases we are just doing
three things with a handful of variables, why shuffle them between
three methods that are entirely dependent on each other, but not
sure what other option there is for a long list of steps like
subquery loading.
Also renamed all the "loader callables" to something descriptive,
might help when they come up in stack traces.