fix in structure alignment of btMultiBodyLinkDoubleData and btMultiBodyDoubleData

causing serialization issue in  URDF/SDF loading in double-precision mode on Windows 32bit.
(it was fine on Mac/Linux 64bit)
bump serialization version to 2.85, as we change the file format
fix in name clash in makesdna.cpp -> intptr_t is already defined.

src/LinearMath/btScalar.h

@@ -29,7 +29,7 @@ subject to the following restrictions:
 #include <float.h>
 
 /* SVN $Revision$ on $Date$ from http://bullet.googlecode.com*/
-#define BT_BULLET_VERSION 284
+#define BT_BULLET_VERSION 285
 
 inline int	btGetVersion()
 {

src/LinearMath/btSerializer.h

@@ -484,7 +484,7 @@ public:
 
 			buffer[9] = '2';
 			buffer[10] = '8';
-			buffer[11] = '4';
+			buffer[11] = '5';
 
 		}