Refactoring patches

[Yuriy Skalko]

>     It is not hard to add `const` again. But here is another important
>     question -- consistency. If you look on any function in LyX with int or
>     bool parameter, it will be without `const` and still is not modified
>     inside the function in 99% cases. I think it is not worth to add it
>     there and to leave here.
> 
>     Also I cannot remember the usage of `const` for value parameters in any
>     common C++ library.
> 
> 
> I wouldn't know about that. But the same reasons to declare variables const would seem to apply here, no?
>
> Riki

Yes, they are similar.

Google C++ Style Guide
(https://google.github.io/styleguide/cppguide.html) says: "For a
function parameter passed by value, const has no effect on the caller,
thus is not recommended in function declarations."

And here is the case against it (linked from above guide):
https://abseil.io/tips/109

But people still have different opinions on it:
https://stackoverflow.com/questions/117293/use-of-const-for-function-parameters

Yuriy