* Two new functions to customize tick labels on any existing plot:
* `wrap_tick_labels`: add text wrapping
* `add_sample_size_to_labels`: add group sample sizes with a `(n=N)` suffix
* Make writing PDF figures a deterministic process and make the PDF text editable.
* Scatterplot improvements:
- Adjust default marker shape and size to work better for most plots.
- Adjust HueValueStyle so that an explicit marker size is not specified there, only a marker size scaling factor. The scatterplot itself is responsible for defining the base marker size, while the palette of HueValueStyles should be drawable at any marker size.
- Change legends so that only one marker is drawn to indicate a group's style.