v2.4. Swipe, press, go!

Updates

• Subject shortcuts now work for opening grade table URLs at /table-grades endpoint
• Long swipe right to open menu (on mobiles)
• Deadlines autoupdate without page refresh (every minute at 00s)
• robots.txt, sitemap.xml added, internal links following and indexing allowed
• Status bar color change on theme switch (for PWA)
• Google Calendar links bugfix: deadline names and descriptions are now properly URL-encoded
• Default theme for new users is forced dark