The autogenerated icons are in most cases ugly, do not conform to the
style of the other icons, and do not respect relative dimensions and
positions. The math icons have a vertical dimension of 19 pixel, defining
a grid that has to be respected for obtaining correct alignment.
The only autogenerated icons that remain are those of the Misc (extra)
toolbar. I plan to also replace them in the near future.
Most images are generated by development/tools/generate_symbols_images.py, but
some were drawn manually. Now there is no image missing from the ones the
script can generate.
