Figures for the Vulkan spec. With the exception of pipeline.pptx, the
current source format for all figures is Inkscape SVG, which is
converted to PDF by the Makefile.

For the pipeline figure, the source is .pptx, which must be manually
exported to PDF (using Powerpoint) and then to SVG (using Inkscape).

Many figures were originally generated in the open source "Dia" drawing
program format. The .dia files are now in oldSource/*.dia, since we're
trying to centralize on Inkscape SVG -> PDF wherever possible. The main
drawback of this is that all the connectivity information in the .dia
file is lost, so modifying these figures in Inkscape will be very
painful. It might be best to edit the original .dia file if anything
nontrivial needs to be done.

To convert .dia -> Inkscape SVG, you can use

    inkscape -f oldSource/file.dia -A file.svg

followed by running Inkscape on file.svg, setting the bounding box of
the figure to the contents using the File / Preferences dialog, and
overwriting file.svg.