Apply bg-mpl-stylesheet colors to matplotlib

[bobleesj]

Problem

Following the tutorials, srmise data/Ag_nyquist_qmax30.gr --no-extract --plot renders:

The color choices aren't optimized.

Proposed solution

Configure https://github.com/Billingegroup/bg-mpl-stylesheets/ within matplotlib and update rendered figures on docs.

[bobleesj]

Please refer to more plots available here: https://www.diffpy.org/diffpy.srmise/tutorial/extract_single_peak.html