Updated simulation testing framework to be used during the development of OMP-18

This document details the framework to be used to simulation test candidate MPs during the development of OMP-18. A summary of assumptions made in this simulation testing framework are listed below. Appendix A provides the full details, with data used listed in the tables at the end of the Appendix. This is a draft, as some parts of this framework may need modifying under alternative hypotheses or under alternative harvest control rules as the development of OMP-18 proceeds.