TODO

 * pattern fill
    * turns out this is a lot easier than I thought it was
    * just like normal fill except the stitch locations in each row are chosen to make a pattern
    * can do this by intersecting the pattern with the shape instead of just a generic grating
 * curved fill
   * use radial fill in inkscape to define center and starting angle
   * the rows of stitches radiate out from a center point
     * otherwise it's just like normal fill
 * start/end points for fills
   * rotation center might work for one of them, but what else can I use in inkscape's UI?
 * keep stitch plan objects and just update the ones that change
   * use md5sum of <path> objects to see what's changed
   * keep stitch plans in a layer above everything else
   * set stitch plans to "noninteractive" so you can click through them to the paths
   * this will make it work more like a "real" embroidery program
   * separate 'export embroidery file' command
 * add option for connection to next patch (jump, trim, or running stitch)