constructor(options, moleculeOptions) {
    this.defaultOptions = {
      scale: moleculeOptions.scale > 0.0 ? moleculeOptions.scale : 1.0,
      fontSize: moleculeOptions.fontSizeLarge * 0.8,
      fontFamily: 'Arial, Helvetica, sans-serif',
      spacing: 10,
      plus: {
        size: 9,
        thickness: 1.0
      },
      arrow: {
        length: moleculeOptions.bondLength * 4.0,
        headSize: 6.0,
        thickness: 1.0,
        margin: 3
      },
      weights: {
        normalize: false
      }
    };
    this.opts = Options.extend(true, this.defaultOptions, options);
    this.drawer = new SvgDrawer(moleculeOptions);
    this.molOpts = this.drawer.opts;
  }
The constructor for the class ReactionDrawer.

@param {Object} options An object containing reaction drawing specitic options.
@param {Object} moleculeOptions An object containing molecule drawing specific options.