Add new array class for systematic decor handles
When trying to construct another algorithm (for multiplicatively combining scale factors) I realised that we don't have a way to read in arrays of systematic decorations that's also configurable by properties. Given that the basic approach here (declaring a vector of strings as a property and then using that to build a vector of handles) is common to all types of read/write decoration/selection handles I opted for a templated class.
This required adding constructors to the basic classes which don't declare properties (this is actually something that has been requested before). Given that it's fairly simple I also added these constructors for the container-level read, write and copy handles.