Bug 916236 - Sketchfab plugin improvements

[t916236] fix minor usability issues with sketchfab plugin; reenable it's ability to be seen
[t916236] custom sketchfab for a blurb about Sketchfab.com
[t916236] sketchfab background fix & URL error
[t916236] editor helper fixes
1.1.92
Fix Bug 917409 - Trim trailing whitespace on urls passed into add clips
review fixes
missed
review fix