.hsg speedup

Speeds up ".hsg" command by sucking out the undocumented JSON from the catalog page.  More cut-and-paste from my fourchan.py module because phenny is weird about module paths and dependencies.

A few times a day (1-3 times out of 1440 daily samples), the catalog JSON does a fucked-up PHP-ism where it publishes the thread-order objet as a mapping of strings instead of an array of integers.  I'm prepared for it, but I felt I should mention it as a heads-up.  Also because fuck PHP -- fuck it in the ear.