* "Find more styles for this site" renamed to "Search on userstyles.org".
* Only appears below search results after "Find more styles" is clicked.
* When style is installed from serach results, it no longer appears in the results.
* "Install" uses already-fetched .JSON data. Avoiding useless call to download().
* in manager use search query like url:https://github.com/openstyles/stylus
* in popup shift-click or right-click on manager button opens it and applies the filter
fixes a rare case of the popup being invoked right after switching to a lazily restored tab-on-demand, which doesn't have an URL yet in FF or has an URL but not the content script in some Chrome forks that implement tab-on-demand
kinda fixes#155
as per spec the fragment portion is ignored in @-moz-document:
https://www.w3.org/TR/2012/WD-css3-conditional-20120911/#url-of-doc
but we still respect url("foo#hash") set in userstyles
because the spec is outdated and doesn't account for SPA sites
collateral damage: simplified URLS.supported()
