Cleanups to RPC code.

This is extracted from a significantly longer RPC change that I put down a couple of weeks ago.

It deletes some unused code, uses Issue and Book a little more, and fixes some long lines and indentation.

Feel free to use this or ignore it!
I don't have a clear picture of the usage model for these.  Is there any chance of a data race with adding to the linked list?  I also notice that the destructor doesn't remove the handler from the linked list.  Could this cause problems during shutdown?