Consistent handling of URL syntax

This is not really going to make things better on its own, but ought to help with a lot of intermittent issues where something fails depending on exactly how it's accessed (for instance, see https://www.librarything.com/topic/351834#n8175620 for a case where multi-word tags fail to show results, but only in certain circumstances, depending on which of the four ways in which the "members in someone's catalog with a given tag" are represented). I bumped into this again today, when I decided to track down why exactly it is that I sometimes see the "X books in all collections" message when I'm viewing a subset of books in one of my own Collections and I sometimes don't (it depends on whether I got there by searching for a tag or by clicking on a tag).

I'm not a front-end person and so the subtleties escape me, but I can't see any reason why there should be four different ways to represent "books in lorax's library tagged with history" in the URL, and plenty of ways that it can make issues harder to track down.