combine efforts on metricsgraphics

[timelyportfolio]

There is another repo from @yutannihilation working on htmlwidgets version of metricsgraphics. Regarding ramnathv/htmlwidgets#64, I thought we should cross-reference https://github.com/yutannihilation/metricsgraphics/issues/3 the projects and let the two developers decide to collaborate if possible.

[yutannihilation]

Thanks @timelyportfolio. I will contribute to this repo if possible 👍

(Since my package is just for my practice of package development, I don't want to compete. Maybe I will rename my package to resolve this name collision.)

[hrbrmstr]

roger that! any contributions are most welcome :-)