Whee, another whole heap of bugfixes (and others).

* Only recognise a message as directed at us when the user uses [,:].
* Wrap all the modMethods in try { ... } blocks.
* Use String.format some more.
* getHTTP(): Wait a tick before reading in the content.
* Stop trying to make `rc js` smart; it didn't work.
* Remove `rc gc`; it was pointless.
* Make isSU() more robust.
* Make an Object.keys() shim.
* A couple (see xkcd) of other bugfixes which I'm too lazy to document here.