Make Google Test build cleanly on Visual Studio 2010, 2012, 2013.

Also improve an error message in gtest_test_utils.py.

include/gtest/internal/gtest-tuple.h.pump

@@ -52,6 +52,14 @@ $$ This meta comment fixes auto-indentation in Emacs. }}
    private:
 #endif
 
+// Visual Studio 2010, 2012, and 2013 define symbols in std::tr1 that conflict
+// with our own definitions. Therefore using our own tuple does not work on
+// those compilers.
+#if defined(_MSC_VER) && _MSC_VER >= 1600  /* 1600 is Visual Studio 2010 */
+# error "gtest's tuple doesn't compile on Visual Studio 2010 or later. \
+GTEST_USE_OWN_TR1_TUPLE must be set to 0 on those compilers."
+#endif
+
 
 $range i 0..n-1
 $range j 0..n