Improve Interactions With the Spectrum Chart

This release primarily builds upon the awesome work of @kenmorte in using D3.js to plot spectra to improve the interactivity with spectra within InterSpec.

Please see https://sandialabs.github.io/InterSpec/releases/ for a full listing of changes.

For Windows (7+) and Linux (Ubuntu 14.0.4+, or similar) unzip the download, and place results wherever you would like; no installation necessary (eg., InterSpec is a portable app).

For macOS (10.10+) download the DMG, open, and drag the InterSpec icon to the Applications folder.