UI/API changes

• Re-enable the "probes shared with me" portlet under /my/
• Fix root server performance map after data layout changes
• Bugfix: favourite/hide did not work in compressed probe list
• Bugfix: apply/cancel buttons refused to work on the probe re-geolocation page
• Bugfix: time travel on various maps did not function
• Fix outgoing social media links from community pages
• Add /api/v2/messages to the API (requires authentication)
• Add a revamped "my messages" page