Thread SEO changes 1.0.13

• Rewrite posts/<postId> links for guests/robots to point to the threads/page#post as microdata causes tons of redirects which eats up the google indexing budget

• Fix XF2.1 support, where #post- bit may not be added to some thread URLs as expected
• Fix canonical URLs would not be generated as expected for post replies for guest user when using the 'share post' widget