Support vector graphics in figures

[warnerjon12]

Figures created using matplotlib.pyplot are saved as png files when exporting. These scaled image files look unprofessional in a pdf output.

For pdf and latex output, it would be better save as a pdf file. Then the axis labels and such are saved using vector graphics so that the resulting file is both smaller and more professional.

[mgeier]

PNG output is indeed the default, but you can select other output formats.

I've collected my findings in https://nbviewer.org/github/mgeier/python-audio/blob/master/plotting/matplotlib-inline-defaults.ipynb, but the TL;DR is:

Add this:

c.InlineBackend.figure_formats = {'svg', 'pdf'}

... to your ipython_kernel_config.py.

[t-makaro]

I believe we do support SVG outputs with the svg2pdf preprocessor. Enabling SVG out from matplitlib is not an nbconvert issue.