Corrections - create a Hawdon method with selectable Rc

Overview

The current method to correct intensity corrections using the Hawdon et al (2014) method hard codes the JUNG cut-off rigidity into the method. We should remove this hard coding and make it soft encoding. That is it should be an option, but default to the Jung value.

Motivation

Allows for future changes in theory that might encourage alternative stations to JUNG - potentially important for sites outside Europe

Technical Requirements

[Key technical requirements]

Dependencies/Interactions

[List any possible dependencies or interactions with other features/modules]

Acceptance Criteria

• A method is available for Hawdon method
• A correction type object is available for Hawdon method

Notes and Future Considerations

Where do we supply the cutoff rigidity? In the YAML (site info) or in the YAML (processing)?