Allow more specific dobjspec, iobjspec

LambdaMOO (and, at the moment, CodeCity) provide exactly three options for dobjspec and iobjspec: `none`, which disallows a direct or indirect object respectively; `this`, which must match the object the verb is on; and `any`, which allows any text (or none) at all.

In many cases—e.g, `$.container.put` any in this, we'd actually like to constrain 'any' a bit. The obvious constraint is that it unambiguously match a single `$.physical` object; the proposed name for this option is "something".

We might wish to be even more general, and allow any `.dobj` and `.iobj` to be set to `$.physical` object, with the verb matching if `dobjstr` and/or `iobjstr` are instances of that prototype—so, e.g., a lock could have `$.lock.unlock` `this` `with` `$.key`.

* [ ] Fix #394, to allow server-supplied options.
* [ ] Modify editors to present relevant options.
* [ ] Modify `$.utils.command.execute` to apply new options.