Addition of constructor variants for QStandardItem class

I tried to clarify the interest for a specific software extension by the discussion topic “Support for constructing QStandardItem objects from QVariant references?” to some degree.

I propose to add constructors for the class “QStandardItem”.

1. Passing parameters like they are used for the function “QStandardItem::setData”.
2. Another possibility would be the data type “QMap<int,QVariant>”, wouldn't it?
3. Would you like to support the initialisation by passing lists (or tuples) of numbers?