Lots of tweaks that make the what/which+noun questions all work

A variety of little things that make questions like this work:

"Which girl do you like?" "What book are you reading?"

NB: which+noun had been previously classified as a _quantity() relation; I changed that to a _det() relation, which makes more sense and is the standard grammatical classification -- they are question-word-determiners.

P.S. Also corrected a few ancient typos that I noticed, so I don't know if those might affect something someday . . .
Some good news for once: it all works now, and it does not seem to generate more than one imperative tag on the interpretation node for sentences with multiple imperative verbs.  I'll commit after I test the other speech-act types . .