Add customisable titles to plots

This is related to #156 but more general. `configured_data` now contains a `dataset` object which is either `all` or `sub` and so various titles could be moved into the function and set depending on the value of `dataset` as the defauly. We could then add the ability customise the titles to whatever the use wants.

Start by locating the plot functions that consume configured_data and inspect how the dataset value, all or sub, currently affects titles. Review issue #156 for context, then trace where titles are assembled and identify the existing plot checks or tests. Done means titles have appropriate all/sub defaults and can be customised by the user across the affected plots.

Written by the indexing model from the issue text.