Explore whether various methods can be automated

[astrofrog]

We should try and figure out which methods can be most easily automated.

The main difficulty is typically figuring out the type of various variables, but if ERFA uses variable names consistently across ERFA we might be able to build up a list of variables that should be int, double, and string to make it easier to generate the wrappers.

[jwoillez]

#6 is a proposed automation for the cython_numpy approach.