Updates to mplot_label

[JackBuckley]

• Allow right/left align of text ✅
• Auto wrap labels, similar to labs_e61
• Use factor levels for colours, i.e. add an option to just supply the variable name
• Add ability to have boxes around labels ✅

Note: Edited by @aaronw22

[aaronw22]

Future notes for when someone gets around to implementing these ideas:

• Can be done by specifying hjust = 0 as an argument in the underlying annotate() function.
• Not sure about the utility of this. Text labels aren't often that long, and squeezing them into little gaps in between lines probably requires a different line break point for each label rather than a consistent one.
• This will be hard to do and might require refactoring the whole thing into a custom geom_, which I don't know how to do, or how to do it without breaking the existing flexibility. Aside: you can get the label names to be correctly ordered if your colour/fill column is an ordered factor and you specify the label names as levels(data$column).
• Might be doable by making it possible to change geom = "text" to geom = "label".

[aaronw22]

FYI @JackBuckley I won't be attempting to implement points 2 and 3 for reasons above.