Clone Timeline: Cleanup

Copy icon now available, even if not logged in. (Useful for grabbing a
subset of Cosmos such as "Humanity".)

Paste icon now hidden unless user has appropriate edit rights to
collection. Previously always displayed if user was logged in.

Quick workaround for displaying paste icon after copy without refresh:
If user has edit rights, now paste icon always displays alongside copy
icon. User is told if attempting to paste without first copying that
user needs to copy to clipboard first.

Per Lori, did not spend time on addressing auto-populating of newly
pasted content. A page refresh or URL change is still required, and the
user is informed of this when pasting.