PyCAM currently shells out to inkscape and pstoedit to read SVG files -
without those helper programs, pycam cannot read SVGs.

The pycam debian package currently Suggests those dependencies, which
means that by default (unless the user explicitly selects them) they
won't be installed.

This commit upgrades the relationship from Suggests to Recommends,
so they'll be installed by default, making SVG work "out of the box".