Add default parameters for guests in a config panel

[papjul]

Currently, default parameters are in constants.
I wanted to control it more easily from the admin, so I created this control panel.

I will let you review it and let me know if you want to integrate it, before I start working on the descendants chart the same way.

[magicsunday]

Hi. I'm sorry it took a while. First of all, thank you for your contribution.

I checked your changes. These do not currently work as the form configuration is already stored in the browser's LocalStorage, i.e. if you change the number of generations from the standard 4 to 6, for example, this is stored in LocalStorage. If you call up the page again, the selection of the generations is now initialized with 6. The pre-assignment from the module does not apply.

Seen in this light, an additional configuration module in the admin area doesn't really seem necessary to me.

[papjul]

This config panel was added as a default (for guests who don't have a local storage yet).

When you first visit the website, this would display in a specific layout with a specific number of generations.
Currently, the default layout is hardcoded in constants, this just makes it configurable.

Of course, when the user decides to change the default parameters, this becomes specific, which is the expected behavior.

I will rename the name of the pull request to clarify.

My use case was that I preferred to have my guests seeing my charts from bottom to top by default (which is a more common layout here in France, than left to right).

[papjul]

Is there anything else I can do to help with this feature? Thank you!

[magicsunday]

I merged it into the current branch 2.1. Sorry it took so long. Thank you for your contribution.