Feature/hr diagram

[jnation3406]

This is the first draft of the HR diagram views. The structure of it should at least provide a strong starting point for implementing it if we don't want to use exactly what is here.

Improvements to be made:

• There is a lot of special code for the interactivity on the plots (range selection on the distance and parallax plots, and ellipse selection and dragging on the proper motion plot). There is probably some room for improvement there to simplify things or rely on other libraries for that.
• The /scripts directory contains a python file that is used to query and generate the /public/parsec.json file used for the isochrone fitting. Since I committed that generated file, this script is just there if we every want to change the parameters and compute a new isochrone dataset.
• It's currently showing a Parallax and Distance plot, but they are redundant so we should probably pick one and remove the other from the plot
• I think its too much info for a tablet. We probably should place the plots in tabs or something if the user is on a small/tablet screen so they can tab through the steps of picking pm/distance ranges, then fitting the isochrone on the CMD.
• I would like to add a button to set the initial isochrone distance param based on the distance ranges the user selects. This would get the initial distance much closer to what the user intended from their min/max selection range.