patch 8.0.1385: Python 3.5 is getting old

Problem:    Python 3.5 is getting old.
Solution:   Make Python 3.6 the default. (Ken Takata, closes #2429)
diff --git a/src/Make_mvc.mak b/src/Make_mvc.mak
index 9c885b9..5a65698 100644
--- a/src/Make_mvc.mak
+++ b/src/Make_mvc.mak
@@ -67,7 +67,7 @@
 #	Python3 interface:
 #	  PYTHON3=[Path to Python3 directory]
 #	  DYNAMIC_PYTHON3=yes (to load the Python3 DLL dynamically)
-#	  PYTHON3_VER=[Python3 version, eg 30, 31]  (default is 35)
+#	  PYTHON3_VER=[Python3 version, eg 30, 31]  (default is 36)
 #
 #	Ruby interface:
 #	  RUBY=[Path to Ruby directory]
@@ -906,7 +906,7 @@
 # PYTHON3 interface
 !ifdef PYTHON3
 !ifndef PYTHON3_VER
-PYTHON3_VER = 35
+PYTHON3_VER = 36
 !endif
 !message Python3 requested (version $(PYTHON3_VER)) - root dir is "$(PYTHON3)"
 !if "$(DYNAMIC_PYTHON3)" == "yes"