FYI, not sure if you’ve come across this yet, but there is an open source C++ lib called Assimp (Open Asset Import Library) under BSD license; http://www.assimp.org/
http://cms.assimp.org/index.php/features
It has support for a substantial list of import and export formats: https://github.com/assimp/assimp
Thought it might be of interest to Transmutr.
