Add option to change superposition parameters from CLI/GUI

[Ninjani]

• This could be a JSON/TOML/any kind of key value file, with the default parameters written in it that you pass in to the CLI via --superpose-parameters.
• Each superposition function needs documentation to make clear what parameters it exposes.
• The GUI needs a dropdown to select the superposition function which should trigger a set of textareas for the corresponding parameters