Plagiarism result “Open in new tab” should be a link, not a button

The Open in new tab buttons on plagiarism result pages are currently <button>s; clicking them opens the result in a new tab. Using <a target="_blank"> instead would provide the user with several options:

• clicking the button would continue to open the result in a new tab;
• now Ctrl+clicking the button would also open the result in a new tab;
• Shift+clicking the button would open the result in a new window (at least in Firefox and Chrome);
• right-clicking (on mobile, long-tapping) the button would open the context menu, with options to open the results in a new tab, new window or new private/incognito window, or to copy, bookmark or share the URL (the latter is especially important in case of JPlag links, because the report viewer rewrites the URL on page load, making it no longer copyable, bookmarkable or sharable).