add option in COLLADA loading to specify client up axis (so that if client=Z and COLLADA =Z, upAxisTransform is identity,
while if client=Y and COLLADA=Y, upAxisTransform is identity etc)
URDF import demo: add COLLADA .dae file support
add FiniteElementMethod demo, extracted from the OpenTissue library (under the zlib license)
don't crash if loading an invalid STL file
add comparison with Assimp for COLLADA file loading (disabled by default, to avoid library dependency)
Gwen: disable some flags that make the build incompatible
