default fill to black per SVG spec

lib/elements/fill.py

@@ -27,7 +27,8 @@ class Fill(EmbroideryElement):
 
     @property
     def color(self):
-        return self.get_style("fill")
+        # SVG spec says the default fill is black
+        return self.get_style("fill", "#000000")
 
     @property
     @param('flip', _('Flip fill (start right-to-left)'), type='boolean', default=False)

lib/extensions/base.py

@@ -158,7 +158,7 @@ class InkstitchExtension(inkex.Effect):
             else:
                 classes = []
 
-                if element.get_style("fill"):
+                if element.get_style("fill", "black"):
                     if element.get_boolean_param("auto_fill", True):
                         classes.append(AutoFill)
                     else: