Move out chosen select code
Remove #completed_fact_check_requests.markLinkedAnchor

The result of this call is to find an element by id matching the
hash portion of the current location (??!) and to add a 'linked' class 
to it. When this section is visible, the hash portion is #fact_checking,
and no element in the source code matches that. I'm assuming this is
legacy and removing it.
Remove unused partial

This partial doesn't seem to be in use anywhere, removing it.
Remove another unused partial
Make admin preview script

Currently, the only required behavior is to initialise the youtube
links.
Move navtab hadling into handler
Renamed chosenSelects helper to formsHelper
Remove edition form sidebar tab fix

The fix was for Chrome. I tested it without this fix and it
seems that whatever Chrome bug caused the issue has been fixed.
Remove admin create-new.js

It no longer had any effect - it used to handle the new document
dropdown menu, but that's now implemented with $().toggler.
Added navBarHelper
Removed js handling .attachment-mode-select

This was legacy and there's nothing left in the project called attachment-mode-select.
Renamed navTabs to tabs.

Because they didn't have anything to do with navigation.
Commit also removes a chunk of JS which duplicates the
mechanism for opening the correct tab based on url hash.