Added square option to list (based on foliojs#1099)

Author: Niek

lib/mixins/text.js

@@ -191,7 +191,9 @@ export default {
         case 'bullet':
           this.circle(this.x - indent + r, this.y + midLine, r);
           this.fill();
-          break;
+        case 'square':
+          this.rect(this.x - indent, this.y, r*3,r*3);
+          return this.stroke();
         case 'numbered':
         case 'lettered':
           var text = label(numbers[i - 1]);