Improve entropy-based crop docs based on feedback.

Fix includes to keep MSVC compiler happy.
Additional memory leak suppressions for latest V8.

src/operations.cc

@@ -1,3 +1,5 @@
+#include <algorithm>
+#include <tuple>
 #include <vips/vips8>
 
 #include "common.h"

src/operations.h

@@ -1,6 +1,7 @@
 #ifndef SRC_OPERATIONS_H_
 #define SRC_OPERATIONS_H_
 
+#include <tuple>
 #include <vips/vips8>
 
 using vips::VImage;