Close #7475: Restore binary & text transform codecs

The codecs themselves were restored in Python 3.2, this
completes the restoration by adding back the convenience
aliases.

These aliases were originally left out due to confusing
errors when attempting to use them with the text encoding
specific convenience methods. Python 3.4 includes several
improvements to those errors, thus permitting the aliases
to be restored as well.

Lib/test/test_codecs.py

@@ -2320,18 +2320,29 @@ bytes_transform_encodings = [
     "quopri_codec",
     "hex_codec",
 ]
+
+transform_aliases = {
+    "base64_codec": ["base64", "base_64"],
+    "uu_codec": ["uu"],
+    "quopri_codec": ["quopri", "quoted_printable", "quotedprintable"],
+    "hex_codec": ["hex"],
+    "rot_13": ["rot13"],
+}
+
 try:
     import zlib
 except ImportError:
     pass
 else:
     bytes_transform_encodings.append("zlib_codec")
+    transform_aliases["zlib_codec"] = ["zip", "zlib"]
 try:
     import bz2
 except ImportError:
     pass
 else:
     bytes_transform_encodings.append("bz2_codec")
+    transform_aliases["bz2_codec"] = ["bz2"]
 
 class TransformCodecTest(unittest.TestCase):
 
@@ -2445,6 +2456,15 @@ class TransformCodecTest(unittest.TestCase):
     # Unfortunately, the bz2 module throws OSError, which the codec
     # machinery currently can't wrap :(
 
+    # Ensure codec aliases from http://bugs.python.org/issue7475 work
+    def test_aliases(self):
+        for codec_name, aliases in transform_aliases.items():
+            expected_name = codecs.lookup(codec_name).name
+            for alias in aliases:
+                with self.subTest(alias=alias):
+                    info = codecs.lookup(alias)
+                    self.assertEqual(info.name, expected_name)
+
 
 # The codec system tries to wrap exceptions in order to ensure the error
 # mentions the operation being performed and the codec involved. We