Minor improvement to extrusion (still not implemented in Jupyter)
Minor improvement to extrusion (still not implemented in Jupyter)

mwcraig/vpython-jupyter,BruceSherwood/vpython-jupyter,BruceSherwood/vpython-jupyter,mwcraig/vpython-jupyter,BruceSherwood/vpython-jupyter,BruceSherwood/vpython-jupyter,mwcraig/vpython-jupyter,mwcraig/vpython-jupyter