Merge pull request #243 from erwincoumans/master

minor cleanup of btgui/demo3 stuff, much more demo cleanup is needed
Merge pull request #245 from erwincoumans/master

split Wavefront .obj to graphics conversion in a reusable file (Wavefron...
Merge pull request #246 from erwincoumans/master

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

disable btInMemorySerializer by default