bump up to Bullet version 2.89 and update serialization structures

src/LinearMath/btScalar.h

@@ -25,13 +25,23 @@ subject to the following restrictions:
 #include <float.h>
 
 /* SVN $Revision$ on $Date$ from http://bullet.googlecode.com*/
-#define BT_BULLET_VERSION 288
+#define BT_BULLET_VERSION 289
 
 inline int btGetVersion()
 {
 	return BT_BULLET_VERSION;
 }
 
+inline int btIsDoublePrecision()
+{
+  #ifdef BT_USE_DOUBLE_PRECISION
+  return true;
+  #else
+  return false;
+  #endif
+}
+
+
 // The following macro "BT_NOT_EMPTY_FILE" can be put into a file
 // in order suppress the MS Visual C++ Linker warning 4221
 //

src/LinearMath/btSerializer.h

@@ -481,7 +481,7 @@ public:
 
 		buffer[9] = '2';
 		buffer[10] = '8';
-		buffer[11] = '8';
+		buffer[11] = '9';
 	}
 
 	virtual void startSerialization()