Sc2Preview constructor Null safety

1. theta
2. theta
3. Sc2Preview
4. Sc2Preview constructor

Sc2Preview class

1. Constructors
2. Sc2Preview
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static properties
12. client
13. keepRunning
14. Static methods
15. getFrames
16. getLivePreview
17. stopPreview