Made it easier to pass a custom lxml parser object into the treebuilder.
Made it easier to pass a custom lxml parser object into the treebuilder.

snarfed/beautifulsoup,h4ck3rm1k3/BeautifulSoup4,snarfed/beautifulsoup,h4ck3rm1k3/BeautifulSoup4,h4ck3rm1k3/BeautifulSoup4