Create RPGCore.DataEditor to edit and maintain game data

[fydar]

Features:

• [x] Basic data editing of lists, dictionaries, objects, and values
• [x] Support for editing data structures as defined in C#
• [x] Saving and loading data to and from files
• [x] Support for editing comments
• [x] Support for abstract and unknown type editing
• [x] Support replacing value types with an alternate type
• [ ] Enum data types (serialized as both string and number)
• [ ] Support change events and model binding
• [ ] Support for generic types
• [ ] Support for data variants
• [ ] Support for polymorphic types
• [ ] Undo/Redo history
• [ ] Support resetting values to their default state
• [ ] Support data variants inside a larger container (e.g. prefabs in the context of a scene)
• [ ] Unique identifiers for values in hierarchy (URLs)
• [ ] Move to a Command/Procedure API for data editing
• [ ] Networked data editing

[fydar]

For Blazor and other modern .NET UI libraries, I should implement INotifyPropertyChanged so that my models can be used in data binding.

I could also explore some alternate data binding approaches.