Add flags to disable bvh and triangleinfomap serialization
btSerializer::setSerializationFlags(flags)
flag can have value BT_SERIALIZE_NO_BVH, BT_SERIALIZE_NO_TRIANGLEINFOMAP
So it is different from the in-place method (btQuantizedBvh::serializeInPlace/deserializeInPlace).
It is also possible to serialize/deserialize just the bvh, using the btSerializer (needs some code snippet/helper)
See also http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=4770
(no motor support or advanced settings yet)
added btStaticPlaneShape serialization
Added toggle in cmake for BenchmarksDemo to enable/disable graphics rendering