[Style] Establish a code style for functions and properties

[shpaass]

I have noticed that many classes have their functions named in camelCase, when the C# convention is PascalCase.
However, renaming it all is going to be such a hell with serialization that even I don't want to do that.

Thus, the intention of this ticket is to just check that most (or all) the code uses camelCase for methods and attributes, and then we add this part into our code style.

[shpaass]

Implemented by #277