Unchecked => opens new tab for search page.
Checkbox hidden if inline results are shown (still shows link to "find styles" which opens a new tab by-default).
* Fetches 'category' for the current URL when popup is first loaded.
* Customizable styles have "Customize" button next to "Install"
* "Customize" button opens a new tab to the style page.
* Removed all console.log() statements (except when `catch()`ing errors).
* "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().