Support options for change-case

[replygirl]

• In individual functions and static methods of CasedObject, the user can specify a second options argument that is passed on to change-case
• When initializing CasedObject, the user can specify additional properties in options that are stored in private _options to later be passed on to change-case
• When interacting with a CasedObject instance, the user can get & set private _options through options