Simple HTML template helper
There should be one or more helpers to create complete HTML documents. These are meant as a convenience for simple applications, not a replacement for user templates in complex applications. Potential syntaxes:
html_document(body, head=None, doctype=doctype("xhtml", "1.0", strict=False), html_attrs=None, head_attrs=None, body_attrs=None, charset=None, lang=None, title=None) }}}
'body' and 'head' are strings, and should be wrapped in literal() if not created by the HTML builder. '*_attrs' are dicts. 'charset', 'lang', and 'title' generate the corresponding <head> features which are recommended by W3C. (Perhaps we should support additional features? But stylesheets, scripts, links, and metas are too complex to generate so they must be specified in 'head'.) But how would it know whether to generate 'xmlns:lang' without understanding the doctype? Perhaps we'd need to give it more doctype intelligence.