Check for minimum required version of Jupyter Lab before trying to install textures
Check for minimum required version of Jupyter Lab before trying to install textures

Fixes #84

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