Bump to 3.6.4rc1

Include/patchlevel.h

@@ -18,12 +18,12 @@
 /*--start constants--*/
 #define PY_MAJOR_VERSION	3
 #define PY_MINOR_VERSION	6
-#define PY_MICRO_VERSION	3
-#define PY_RELEASE_LEVEL	PY_RELEASE_LEVEL_FINAL
-#define PY_RELEASE_SERIAL	0
+#define PY_MICRO_VERSION	4
+#define PY_RELEASE_LEVEL	PY_RELEASE_LEVEL_GAMMA
+#define PY_RELEASE_SERIAL	1
 
 /* Version as a string */
-#define PY_VERSION      	"3.6.3+"
+#define PY_VERSION      	"3.6.4rc1"
 /*--end constants--*/
 
 /* Version as a single 4-byte hex number, e.g. 0x010502B2 == 1.5.2b2.

README.rst

-This is Python version 3.6.3
-============================
+This is Python version 3.6.4 candidate 1
+========================================
 
 .. image:: https://travis-ci.org/python/cpython.svg?branch=3.6
    :alt: CPython build status on Travis CI