Accept header parsing fixes. Now return first acceptable match rather than last. If not acceptable match in accept, 406 error returns list of acceptable types as text string. application/xml is listed in acceptable types only if dicttoxml is installed. Handle q > 1.0 by demoting q factor to 0.0001 making it unusable. Test cases for all this code. XML is commented out as we don't install dicttoxml.py.

def audit_html_files(db, cl, nodeid, newvalues):
    if 'type' in newvalues and newvalues['type'] == 'text/html':
        newvalues['type'] = 'text/plain'
    

def init(db):
    db.file.audit('set', audit_html_files)
    db.file.audit('create', audit_html_files)