Improve case style of all input parameters

[sebproell]

Once we got rid of dat (#598), we could easily unify the case style of all parameters and sections/groups with the help of the input upgrade mechanism by @gilrrei (WIP, not yet pushed, I believe). I think this would be a good idea to

• increase the searchability by using snake_case and naming parameters the same as we name the respective data in code. This works especially nicely if you bind your input data to struct fields of the same name.
• allow for generation of dataclasses in python, if our parameters and groups have legal identifier names (no /). Again, something that @gilrrei already has drafted.
• increase the readability. UPPERCASEWITHOUTANYSPACES is just annoying.
• ...?

I guess the way to do that would really be to change all parameters at once and provide the respective transformation in the upgrade mechanism.

@bwirthl already started renaming "her" parameters, and it is so much better this way (IMO).

[gilrrei]

@sebproell the update mechanism is on the fourcipp main for some time now. It hasn't been deployed since no input file version scheme was agreed upon.

Regarding the naming of input stuff, I compiled some inconsistencies in #317.

One point that might be important to do before your proposed change (or simultaneously) is nest the sections that contain a slash in the name. Otherwise these would be invalid variable names as well.

[sebproell]

@gilrrei Once we have the input_version (#74), we could do the nesting transformation as one of the first steps to test how well the upgrade mechanism works.

[isteinbrecher]

I am very hesitant with a change like this. This works well if you work with input files, but if you work with scripts, you will have to adapt each script by hand. We already had to do that for the switch to yaml, and now this would mean that we have to do it again, for a purely cosmetic change.

[mayrmt]

@isteinbrecher, thanks for bringing your concerns to attention! I understand them and feel very similar about this.

[ischeider]

Even though I am a supporter for most new input file features, I also feel that just changing names may be annoying for some people, not only for the power users using scripts. When we refactor features we should have an eye on the affected parameters, but just so seems too ambitious to me as well.