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.
Adding line about setting quality in config.
Fixing docstring.
Merge pull request #4920 from ellisonbg/pdf-formatter

Adding PDFFormatter and kernel side handling of PDF display data