Update to codemirror 4

Update to codemirror 4.6 and update most notebook to work wiht it
this include keyevent that where triggerd twice and the re-writing of
ipython-gfm anf ipython mode to work with require.
update to components master
rework keyboard management to avoit completer and up/down bugs
protect agains undefined
handle somehting selected and multiple cursors and 4 tabs show content in pager
Merge remote-tracking branch 'carreau/cm4' into font_awesome_update
update font-awesome