Prepare 1.6.4

ChangeLog

@@ -5,7 +5,13 @@ Pylint NEWS
 What's new in Pylint 1.6.4?
 ===========================
-Release date: tba
+Release date: 2016-07-19
+
+    * Recurse into all the ancestors when checking if an object is an exception
+
+      Since we were going only into the first level, we weren't inferring
+      when a class used a metaclass which defined a base Exception class
+      for the aforementioned class.
 What's new in Pylint 1.6.3?

pylint/__pkginfo__.py

@@ -12,7 +12,7 @@ from os.path import join
 modname = distname = 'pylint'
-numversion = (1, 6, 3)
+numversion = (1, 6, 4)
 version = '.'.join([str(num) for num in numversion])
 install_requires = [