Amendments to various non-working WordPress elements

Updated support for post thumbnails so they are now displayed on both summary pages
and content pages (smaller on summaries)
Removed unnecessary code from the content-video template partial
Added post pagination to the loop-content partial so that paginated posts can be
viewed correctly
Added autoembed to the_excerpt through a filter in the theme_support function
Fully cleaned up the excerpt code used in FSESU_Theme class by adding a custom
trim_excerpt function that allows html tags, sets the read more text and defines
the excerpt length
Adjusted the comment list to use short pings