Split Bullet/src/LinearMath/btSerializer.cpp into btSerializer64.cpp to make it easier to rebuild serialization structure.

Add several MSVC optimization flags to cmake.
Bump up VERSION because serialization format changed
Expose btScalar& jointMaxForce, btScalar& jointMaxVelocity to 'getJointInfo2' API, add backwards compatibility to examples\Importers\ImportURDFDemo\URDFImporterInterface::getJointInfo.

pybullet: expose 4 more fields to getJointInfo: jointLowerLimit/jointUpperLimit/jointMaxForce/jointMaxVelocity
fix performance issue in CMD_ACTUAL_STATE_UPDATE_COMPLETED

src/LinearMath/CMakeLists.txt

@@ -11,6 +11,7 @@ SET(LinearMath_SRCS
 	btPolarDecomposition.cpp
 	btQuickprof.cpp
 	btSerializer.cpp
+	btSerializer64.cpp
 	btThreads.cpp
 	btVector3.cpp
 )