Added a basic COLLADA .dae importer mainly to support URDF loading (URDF can refer to COLLADA .dae or STL .stl for mesh support)
It is fairly limited, only supports loading <geometry> with triangulated meshes, no material loading
I will extend this with COLLADA Physics support.
fix mac build
remove unnecessary header
add basic concept demo, Coordinate System for a start.
set the up axis for some of the demos.
Merge pull request #273 from erwincoumans/master

COLLADA .dae importer for URDF, Basic Coordinate System demo
fix build
Merge branch 'master' of https://github.com/erwincoumans/bullet3
Merge pull request #275 from erwincoumans/master

fix build