code: function SiteBuilder(config, fileMap) {
    this.config = config;
    this.root = config.root;
  
    var helperFile = path.join(this.root, '_lib', 'helpers.js');
    if (existsSync(helperFile)) {
      userHelpers = require(helperFile);
    }
  
    var filterFile = path.join(this.root, '_lib', 'filters.js');
    if (existsSync(filterFile)) {
      userFilters = require(filterFile);
    }
  
    var postFilterFile = path.join(this.root, '_lib', 'post-filters.js');
    if (existsSync(postFilterFile)) {
      userPostFilters = require(postFilterFile);
    }
  
    this.outputRoot = config.output;
    this.fileMap = fileMap;
    this.posts = [];
    this.helpers = helpers;
    this.events = new EventEmitter();
    this.includes = {};
  
    this.loadPlugins();
  }
docs: Initialize `SiteBuilder` with a config object and `FileMap`.
  
  @param {Object} Config options
  @param {FileMap} A `FileMap` object
  @api public