2to3
urllib syntax
2to3
rewrote update_prompt_number for new plugin api
python3 version of websockets
partially 2to3-version of nbformat
convert all nbformat files
init
save notebooks
fix cell numbers
set pager text command
fix open as ipnyb file command
a todo
moved all converted nbformat files to external/nbformat3
removed backup files
Merge remote-tracking branch 'upstream/master' into python3

Conflicts:
	TODO.md
added python2 nbformat files
updated nbformat from python source
update python3 nbformat files
changed script to copy and convert python nbformat files