problem tracking xml:base and xml:lang if element declares it, child
doesn't, first grandchild redeclares it, and second grandchild doesn't;
refactored date parsing; defined public registerDateHandler so callers
can add support for additional date formats at runtime; added support
for OnBlog, Nate, MSSQL, Greek, and Hungarian dates (ytrewq1); added
zopeCompatibilityHack() which turns FeedParserDict into a regular
dictionary, required for Zope compatibility, and also makes command-
line debugging easier because pprint module formats real dictionaries
better than dictionary-like objects; added NonXMLContentType exception,
which is stored in bozo_exception when a feed is served with a non-XML
media type such as 'text/plain'; respect Content-Language as default
language if not xml:lang is present; cloud dict is now FeedParserDict;
generator dict is now FeedParserDict; better tracking of xml:lang,
including support for xml:lang='' to unset the current language;
recognize RSS 1.0 feeds even when RSS 1.0 namespace is not the default
namespace; don't overwrite final status on redirects (scenarios:
redirecting to a URL that returns 304, redirecting to a URL that
redirects to another URL with a different type of redirect); add
support for HTTP 303 redirects