Handle exporting of empty paths.

examples/SVG Export/Empty Path Testing.html

@@ -19,6 +19,8 @@
 		var path2 = new Path(segments);
 		path2.strokeColor = 'yellow';
 
+		var path3 = new Path();
+		
 		document.getElementById('svg').appendChild(project.exportSvg());
 	</script>
 	<svg id="svg" style="width: 500px; height: 500px"></svg>

src/svg/SvgExport.js

@@ -182,6 +182,8 @@ new function() {
 			return  segments.length === 4 && path._closed
 					&& isColinear(0, 2) && isColinear(1, 3)
 					? 'rect'
+					: segments.length === 0
+						? 'empty'
 						: segments.length >= 3
 							? path._closed ? 'polygon' : 'polyline'
 							: 'line';
@@ -236,6 +238,8 @@ new function() {
 			angle = determineAngle(path, segments, type, center),
 			attrs;
 		switch (type) {
+		case 'empty':
+			return null;
 		case 'path':
 			attrs = {
 				d: getPath(path, segments)