Put CGI parameters into browse URLS

[jesserodin]

When browsing in general, put a CGI search term in the URL.

Composers
Genres
No of voices

Also:

1. Rename https://josquin.stanford.edu/performance/ AS https://josquin.stanford.edu/texted-editions

2. For the latter, make it possible to link directly to the list of pieces, as in
   https://josquin.stanford.edu/texted-editions/list