Log Message:
Update to 5.1.2. From the changelog:

* Minor changes to the documentation
* Strip potentially dangerous ENTITY declarations in encoded feeds
* feedparser will now try to continue parsing despite compression errors
* Fix issue 321 a little more (the initial fix missed a code path)
* Issue 337 (`_parse_date_rfc822()` returns None on single-digit days)
* Issue 343 (add magnet links to the ACCEPTABLE_URI_SCHEMES)
* Issue 344 (handle deflated data with no headers nor checksums)
* Issue 347 (support `itunes:image` elements with a `url` attribute)
* Fix mistakes, typos, and bugs in the unit test code
* Fix crash in Python 2.4 and 2.5 if the feed has a UTF_32 byte order mark
* Replace the RFC822 date parser for more extensibility
* Issue 304 (handle RFC822 dates with timezones like GMT+00:00)
* Issue 309 (itunes:keywords should be split by commas, not whitespace)
* Issue 310 (pubDate should map to `published`, not `updated`)
* Issue 313 (include the compression test files in MANIFEST.in)
* Issue 314 (far-flung RFC822 dates don't throw OverflowError on x64)
* Issue 315 (HTTP server for unit tests runs on 0.0.0.0)
* Issue 321 (malformed URIs can cause ValueError to be thrown)
* Issue 322 (HTTP redirect to HTTP 304 causes SAXParseException)
* Issue 323 (installing chardet causes 11 unit test failures)
* Issue 325 (map `description_detail` to `summary_detail`)
* Issue 326 (Unicode filename causes UnicodeEncodeError if locale is ASCII)
* Issue 327 (handle RFC822 dates with extraneous commas)
* Issue 328 (temporarily map `updated` to `published` due to issue 310)
* Issue 329 (escape backslashes in Windows path in docs/introduction.rst)
* Issue 331 (don't escape backslashes that are in raw strings in the docs)