Adopt more conventions and strategies from lightkurve

[gully]

Lightkurve is great, well-liked, and battled-tested. While it applies to time-series photometry, many of its signal processing steps could be directly applied to muler, with some modest alterations. A good example is plotting, as brought up by @ericasaw in #142.

I encourage prospective contributors to muler consider experimenting with lightkurve first to see what kind of user experience we strive for, and then skimming through the source code to see a benchmark for conventions, style, and modularity.

If folks are keen on this, I suggest we use this thread to collect examples of lightkurve code that we could port to muler. We already have .flatten(). We could add .bin(), .plot() for example.