Marker styles for plotting routines

Summary

Marker styles for plotting routines, in addition to line styles.

Current behaviour/setbacks

With only line styles able to change, I can't highlight the individual points. Highlighting this is useful especially when the data points are low resolution.

Desired behaviour/advantages

Option to customise marker styles in addition to line styles.

Implementation sketch

In the plotting function of each routine (should be on the bottom), add marker_style option tied to matplotlib's marker property.