Merge pull request
#884 from fperez/nb-usability...
Merge pull request
#884 from fperez/nb-usability
Various Notebook usability fixes:
- add kernel restart dialog confirmation (it destroys the user session)
- add missing keybindings
- change language from 'terminal mode' to 'in-place execution' which is more descriptive
- adjust spacing/padding and colors slightly for readability and better use of space in small screens.
- add line numbering toggle to code cells. Triggered with C-m-l.
- show keybindings in monospaced font.
- add QuickHelp button that is always visible and at the top.
- add missing keybindings for kernel interrupt/restart from the kbd.
