Added x3dom-full 1.6.1
Added x3dom renderer (http://www.x3dom.org)
Added x3dom cylinder head example
Added a unittest for x3dom renderer
Fixed in small bug in threejs_renderer
Merge pull request #41 from tpaviot/review/x3d-renderer

review/x3d renderer
Modify Travis config files to support
both py2 and py3
Small fix in Cmake List; tweaked swig -py3 option