notebook docs touchup

closes #3902

incorporating doc changes from David Sanders, minor revisions my own

-@ivanov
major doc update for 1.0 release

- added links to example notebooks on nbviewer
- removde unnecessary file and parts of files
- put old htmlnotebook.html redirect (for Notebook Help urls in 0.13.x)
- moved working_remotely to public_server
- re-arrangement of notebook connection stuff
- more cross-referencing of documentation sections
- made links to magic command explanation in tutorial
- and many more changes...