Categorized People List handling

[mikedilger]

trafficstars

• [x] Handle incoming categorized person list contents as either NIP-04 or NIP-44, and include those as secret entries
• [x] Produce categorized list events with secret entries encrypted in the contents as NIP-04 (until the world changes to NIP-44)
• [x] The d-tag on these events should be the name of the list from PersonList.name()
• [x] If we pull in an event with a d-tag we haven't seen before, auto-assign it to the next custom slot holding a default name.
• [ ] Provide the ability to merge lists. People may create similar lists on two different clients with two different names and want to merge them.
• [ ] Provide the ability to delete lists. This should reset the custom name setting too.

This issue replaces #18

[mikedilger]

I ticked off things completed on the back end. The front end work is still in progress on making use of these lists, buttons to merge and publish per list, etc.