Clean up `inst`

[samussiah]

The htmlwidgets collection has been moved to safetyCharts so it's no longer needed in safetyGrahpics right? Is part of the UI htmlwidgets-driven?

[jwildfire]

Yeah, we need to do this (and delete various other orphaned files) before v2 goes out the door.

[jwildfire]

Expanding scope a bit to clean up all of /inst.