API: Support RE.subscribe(func).
API: Support RE.subscribe(func).

*The original usage, RE.subscribe(name, func), is supported with a warning.*

All tests pass, unchanged.

This is a case of the adage, "You design the most important part of your
software at the beginning, when you understand it the least." The switch on
'name' is rarely used.

ericdill/bluesky,ericdill/bluesky