Info constructor Null safety

1. equizz
2. general_information
3. Info
4. Info constructor

Info class

1. Constructors
2. Info
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static properties
12. categories
13. difficulties
14. difficultiesComplete
15. durations
16. eloMatrix
17. Static methods
18. getCategoriesJson
19. getEloColumn