stop edit description handlers from piling up

each load notebook was adding another handler
thus N "please enter new name" dialogs were popping up!
move file_list stuff to keep notebook update chain contiguous
enable jqtree updateNode and fix some things it breaks
overhaul history display in tree

don't recreate whole history (fixes #109)
in fact, don't reload history unless we have none
incrementally add/remove history nodes
(this may or may not help with speed but definitely helps stability)

always show history node if current

clearly distinguish add-history modes with 'whither'

fix inconsistent amount of history
(and work around inconsistent github history amounts)

debug mode colors for seeing what history's been added
restore the case where we do need to delete & recreate

history node... when moving folders
Merge branch 'develop' of https://github.com/att/rcloud into develop