ensure scp destination directories exist (with mkdir -p)

in SSH launchers.

As described in #3411

closes #3411
Expose kernel_info method on inprocess kernel client

Closes gh-5031
Clear timeout in multi-press keyboard shortcuts.
only validate package_data when it might be used

closes #5046
Add edit/command mode indicator.
Delete old timeout.
Removed #4986
Revert #3552
New 'flex' support

http://dev.w3.org/csswg/css-flexbox/
https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Flexible_boxes
fab css
Adding PDFFormatter and kernel side handling of PDF display data.
Adding support for multiple figure formats in InlineBackend.
Making figure_format config=True.
Adding top level IPython.display.select_matplotlib_formats.
Docstring improvement.
Refining the matplotlib APIs in IPython.display.
Adding basic append_pdf in OutputArea.
Spinning sun + nothing for command mode.
Add kernel_info method to InProcessShellChannel
Convert tabs to spaces