Refactor plotting functions, including the following:
Add docstrings.
Add tests.
Remove plotting-specific information from other classes where possible. Ideally reduce the number of inputs a plotting function requires by accepting the class instance as input and reading required values from there.
Allow for custom plottings by returning the axis object in each function.
Consider replacing the PlotManager class with a series of functions (is there any advantage to these being class methods?)
Refactor plotting functions, including the following: