* RangeArgument.cs: A new range argument

[filipejsbrandao]

Testing the waters with the a new range argument.

• AddCubeSliders.cs: A new example file with a range argument

• DataAccess.cs: Changed to include the new range argument

• NavMenu.razor: Added the range argument

[filipejsbrandao]

The range argument extends the number of fields of the AbstractArgument class. It works because the type of the new fields is the same. I think that to implement something like a dropdown with options we would need to do some changes to the GetData() method to allow lists or dictionaries of the same type as the defaultValue. Other alternatives are welcome