Display post formats in the posts list table.

props nacin, garyc40, DrewAPicture, wonderboymusic, aaroncampbell.

fixes #16047
"Lookup" is a noun. "Look up" is the verb form. If you doubt me, you should have lookuped in a dictionary.

props johnbillion, SergeyBiryukov. fixes #22386
Open external links to plugin homepages, plugin author homepages, and theme author homepages in a new window/tab. props SergeyBiryukov. fixes #20839.