Fixed compiling Box2D on some platforms (memory.h doesn't exist in every build environment)

src/libraries/Box2D/Collision/Shapes/b2ChainShape.cpp

@@ -19,7 +19,7 @@
 #include <Box2D/Collision/Shapes/b2ChainShape.h>
 #include <Box2D/Collision/Shapes/b2EdgeShape.h>
 #include <new>
-#include <memory.h>
+#include <string.h>
 
 b2ChainShape::~b2ChainShape()
 {

src/libraries/Box2D/Collision/b2BroadPhase.cpp

@@ -17,7 +17,7 @@
 */
 
 #include <Box2D/Collision/b2BroadPhase.h>
-#include <memory.h>
+#include <string.h>
 
 b2BroadPhase::b2BroadPhase()
 {

src/libraries/Box2D/Collision/b2DynamicTree.cpp

@@ -17,7 +17,7 @@
 */
 
 #include <Box2D/Collision/b2DynamicTree.h>
-#include <memory.h>
+#include <string.h>
 
 b2DynamicTree::b2DynamicTree()
 {

src/libraries/Box2D/Common/b2BlockAllocator.cpp

@@ -18,7 +18,7 @@
 
 #include <Box2D/Common/b2BlockAllocator.h>
 #include <limits.h>
-#include <memory.h>
+#include <string.h>
 #include <stddef.h>
 
 int32 b2BlockAllocator::s_blockSizes[b2_blockSizes] = 

src/libraries/Box2D/Common/b2GrowableStack.h

@@ -19,7 +19,7 @@
 #ifndef B2_GROWABLE_STACK_H
 #define B2_GROWABLE_STACK_H
 #include <Box2D/Common/b2Settings.h>
-#include <memory.h>
+#include <string.h>
 
 /// This is a growable LIFO stack with an initial capacity of N.
 /// If the stack size exceeds the initial capacity, the heap is used