We now enable the Add button after selection
Progress towards Add Property

Wrote the API and back end.

Introduced the RxAttr() gadget (which should have occurred to me
before), and used that to help make the "Add" button work.
Massive refactor of Add Property

Decided to get more serious about Rx.  Created a display.rx package for
Rx Gadgets.

Created RxSelect, which publishes a select tag as a bunch of reactives.

Created RxDiv, which is what WrapperDiv probably should have been from
the beginning.

Spent a *lot* of time chasing down bugs, but the resulting code is
nicely elegant.

Began to introduce jqExt2, for actual jQuery extensions.

Introduced spewing(), as the quick way to wrap a block with some debug
spew.
Finish the moves.