Add serialization support for btGeneric6DofSpring2Constraint
Attempt to re-order serialization data so it can be serialized in-memory (for deep copy)
Update btSerializer.h

fix compile error in LinearMath/btSerializer.h
minor cleanup of btgui/demo3 stuff, much more demo cleanup is needed
moved some files in btgui/Bullet3AppSupport
Merge pull request #243 from erwincoumans/master

minor cleanup of btgui/demo3 stuff, much more demo cleanup is needed
split Wavefront .obj to graphics conversion in a reusable file (Wavefront2GLInstanceGraphicsShape.*)
Merge pull request #245 from erwincoumans/master

split Wavefront .obj to graphics conversion in a reusable file (Wavefron...
add btInMemorySerializer (experiments, allows for in-memory deep copy of worlds, bypassing the BulletFileLoader mechanism)
add btCollisionWorldImporter that can load a .bullet file, or use the btInMemorySerializer for deep-copy
Merge pull request #246 from erwincoumans/master

add btInMemorySerializer (experiments, allows for in-memory deep copy of...
disable btInMemorySerializer by default
Merge pull request #247 from erwincoumans/master

disable btInMemorySerializer by default
fix btInMemorySerializer
disable btInMemorySerializer by default
Merge pull request #248 from erwincoumans/master

 	fix btInMemorySerializer but disable btInMemorySerializer by default