only calc panel width if a collapse is changing something

to stop simple updates from moving columns around, fixes #847

when collapsing or uncollapsing, see if the panel is already
collapsed.  do not save the setting, and do not do change
column width, if there is no change.
add rcloud.config.get.alluser.option

for fetching system-wide options from RCS
generalize friend-tree duplication and add featured notebooks

closes #1012
also load_tree was full of all this promisified code that
didn't need to be. back to just generating a tree after
fetching all the data and options!
update featured users tree too
do not show featured users if there aren't any

and don't crash!