Reorder of serverdlg bits

[pljones]

Short description of changes

This starts to get to making actual changes in behaviour of the server dialog code.

I STRONGLY recommend viewing each commit separately before viewing the full diff. The aim was to keep each change small, self-contained and then test so that I was confident I'd not broken anything along the way.

(Admittedly, skimming the full diff now, it doesn't look too bad...)

Context: Fixes an issue?

The aim is multifold but primarily to make it easier to tie the UI as displayed to the code that implements it. This means code gets moved around quite a lot, meaning the diff looks like inserts/deletes, unfortunately -- hence the recommendation above.

It also fixes a few bits (like adding missing "What's This" help).
->

Does this change need documentation? What needs to be documented and how?

New / changed translation(s). May need new screenshots. (I've been using it too long to remember, now.)

Status of this Pull Request

Ready to merge (IMO).

Checklist

• I've verified that this Pull Request follows the general code principles
• I tested my code and it does what I want
• My code follows the style guide
• I waited some time after this Pull Request was opened and all GitHub checks completed without errors.
• I've filled all the content above

[pljones]

And once this is done

• https://github.com/pljones/jamulus/tree/feature/server-list-persistence-ui
  This updates the Server UI to add the Server List persistence file -- and makes some other significant changes, like getting rid of the "register server" checkbox and using the drop down with a new AT_NONE type (meaning not registered).
  

[pljones]

Something I've not done is change "Custom Directory" to (or back to...) "Custom Directory Server Address"... but in context here, I think that would be a good idea.

(OK, done as part of feature/server-list-persistence-ui, along with slight adjustment to the "Language" dropdown, which looked a bit odd before.)

[softins]

Just a few initial comments for consideration before doing a final review. Looks good in general.

[ann0see]

Hmm. Not 100% sure about the concept of setting a list to "Unregistered". Basically it seems a bit unintuitive if we think about the private/registered(=public) server concept. How do we ensure that the user knows "Unregistered" = private server? I think the behaviour we had until now was a little bit more intuitive.

[ann0see]

… and I mean, putting the custom server textbox into another tab feels a bit strange.

[pljones]

Hmm. Not 100% sure about the concept of setting a list to "Unregistered". Basically it seems a bit unintuitive if we think about the private/registered(=public) server concept. How do we ensure that the user knows "Unregistered" = private server? I think the behaviour we had until now was a little bit more intuitive.

It solves an existing defect - go read the discussions.

(It's probably easier to wait until this get to PR so you can try running it -- or jump on the latest build on my branch.)

[pljones]

… and I mean, putting the custom server textbox into another tab feels a bit strange.

It hasn't moved.