Refactor Generator Nodes

[trisyoungs]

We have a stock of GeneratorNodes which need to be removed / refactored into Nodes.

• Add (now InsertNode)
• AddOnSphere (replace with additional Insert input determining surface or region on which to insert)
• AddPair (should be made redundant by Insert and MoleculeSets)
• Box (now SetBox)
• CoordinateSets
• Copy
• CustomRegion
• CylindricalGlobalPotential
• CylindricalRegion
• GeneralRegion
• ImportCoordinates (now one of many ImportXXXStructure nodes)
• IterateSelection
• Parameters (superseded by NumberNodes)
• Pick
• PickProximity
• PickRegion
• RegionalGlobalPotential
• Remove
• RestraintPotential
• RotateFragment
• Select
• SizeFactor
• SphericalGlobalPotential
• Temperature (probably irrelevant now if we make temperature local to algorithms rather than Configurations)
• Transmute