Add cutscene implementation

[pietbrauer]

Currently there is no implementation for cutscenes, but it seems it should be easy to add it (Reference).

Cutscenes are located between one or more .playgroundpages and can illustrate the things discussed in the following pages.

Their Manifest.plist file is simple:

Key	Type	Description	Required
CutsceneReference	String	The file path for the main page of a cutscene. See CutsceneReference Key.	✓
Name	String	The name displayed in the user interface. See Name Key.	✓

And the folder structure is as follows:

└── Intro.cutscenepage
    ├── Manifest.plist
    └── Resources
        └── hello.html