Lots of bug fixes:
* properly handle case where stroke width is not set (defaults to 1 per SVG spec)
* properly handle case where <svg> width and height not set (defaults to viewbox)
* properly handle case where fill is not set (defaults to "black" rather than "none")
* show error message (rather than crashing) if satin column set for a path with only one subpath
* don't leave the simulate window around after "use last settings"
* show a useful error message in Params if the user hasn't selected anything embroiderable
Huge new feature: **realistic rendering**! When printing, select the
"Realistic" checkbox to switch a preview image to realistic thread
rendering. Note that rendering can take awhile, so don't be surprised
if the view doesn't change for 10-20 seconds. Gives equally good
results in "print to PDF" or direct printing. Realistic images are
rendered at 600dpi.
