Introduced the repository properties.
Implemented the repository properties of UnitOfWork.
Updated Experiment to v2.1.5.
Addressed covariance for IModelCommand.
Introduced the Result2 property.
Renamed the Result property.
Renamed the Result2 property to Result.
Implemented the Execute(Article) method of

the CanModifyConfirmableCommand class.
Changed the generic type argument.
Introduced the new constructor of CanModifyConfirmableCommand.
Implemented the Execute(Keyword) method.
Implemented the Execute(Bookmark) method of

the CanModifyConfirmableCommand class.
Addressed gurd clauses.
Implemented the Execute(User) method of

the CanModifyConfirmableCommand class.