GlobalSim - mostly modifications arising from using a Run 4 menu
This MR deals with some of the issues which arose when GlobalSim interacted with a Run 4 menu. The most important of which was that, temporarily and for development purposes, the GlobalSim configuration code assumed that a number of named Algorithms were present in the menu, and configured subgraphs hanging below these Algorithms. Some of these were not present in the menu used for these tests. The fix was request such subgraphs instead of requiring them.
In the future, it is intended that all Algorithms required by the menu will have been implemented. That is a missing Algorithm is an error, rather that merely not yet implemented.