Add unicode_std_stream function to write UTF-8 to stdout/stderr
Use unicode_std_stream in nbconvert stdout writer

Closes gh-4578
Documenting codemirror shorcuts.
Fixing language problems and redesign of the table.
New redesing of the table to get a better visualization.
Fixing some language mistakes.
Changing Ctrl-Shift order in redo shortcut.
test that rename fails with 409 if it would clobber

(test already passes, but it should still be tested)

closes #4600
Merge pull request #4601 from minrk/test-rename-existing

test that rename fails with 409 if it would clobber
Added link to shorcuts in the notebook menu.
Tutorial doc should link to user config intro

Not to the config development details.
Merge pull request #4607 from takluyver/tutorial-config-link

Tutorial doc should link to user config intro
Merge pull request #4591 from damianavila/cm_keys

Documenting codemirror shorcuts.
Merge pull request #4581 from takluyver/i4578

Writing unicode to stdout
Fix bytes regex for Python 3.

Closes gh-4602
Merge pull request #4609 from takluyver/i4602

Fix bytes regex for Python 3.
Fixed #4494 -- Added warning mssge if same notebook is uploaded.