The proposed PR removes the following unittest features:

* "fail*" and "assert*" aliases of TestCase methods.
* Broken from start TestCase method assertDictContainsSubset().
* Ignored TestLoader.loadTestsFromModule() parameter use_load_tests.
* Old alias _TextTestResult of TextTestResult.

Most features were deprecated in 3.2, "fail*" methods in 3.1, assertNotRegexpMatches in 3.5. They were kept mostly for compatibility with 2.7 (although some of them were new in Python 3 and not compatible with 2.7).

Using deprecated assertEquals instead of assertEqual is a common error which we need to fix regularly, so removing deprecated features will not only make the current code clearer, but save as from future errors.