How a finished salience map is brought into a usable range.

Mirrors tbp/monty/frameworks/models/salience/strategies/vocus2/vocus2.py::Normalize, a Protocol in Monty so a config can name how the map is normalised. It is a behaviour here: a salience map in, a salience map out.

Monty's two are range_normalize/1 and no_normalize/1 in Monty.Frameworks.Models.Salience.Strategies.Vocus2. Range normalisation is the default because a salience module's caller decides where to look by comparing salience values, and an unnormalised map's scale depends on the brightness and detail of the view rather than on how interesting it is.