Introducing VortexSettings.. redux

[disc0infern0]

Introducing VortexSettings

This change extracts the system wide parameters of a vortex system into its own struct, referenced from within the VortexSystem by the new variable settings. Doing the above removes the need for invoking .makeUniqueCopy() on the VortexSystem The seemingly large change is, after creating of VortexSettings, mostly changing references from VortexSystem to the new VortexSettings, except for the following:-

• Shape, Color, ColorMode and SpawnOccasion are relocated to be within VortexSettings, as they relate to parameters in VortexSettings with those types.
• The VortexView init now accepts a type of VortexSettings.
• Presets and the Sandbox have been updated to use the VortexSettings initialiser, and for the presets, Xcode previews have been added.
• secondarySystems is replaced by secondarySettings, and the spawn method in VortexSystem-Behaviour is updated as a result.
• Readable and writable dynamic lookup has been to VortexSystem to minimize the impact on existing code. (References to secondarySystems will have to be updated)
• minimal updates to Readme.

[ Includes one tweak to the fireflies preview, to tidy up code relating to showing the instructions ] [ Odd shaped initialisers from previous PR has been removed.]