Proof independent settings seem to be no longer saved about key

[Drodt]

It seems that settings in general are not saved. Changing the appearance or font size also gets lost.

[Drodt]

I seem to have found the point where it goes wrong (using the extension example):

1. ExtensionSettings are added to ProofIndependentSettings
2. The lastReadedProperties are read to extract extension settings
3. Reading is done by AbstractPropertiesSettings#readSettings(Properties)
4. It looks for key "disabled" to get disabled extensions
5. Disabled extensions are actually under Extensions > disabled in the JSON file
6. No property for "disabled" is found; use default

I think the JSON file is not properly read and reading it as Properties seems incorrect. Iirc, @wadoon implemented this. I am not familiar enough to change it.

[unp1]

@Drodt Thanks for looking into it!

[FliegendeWurst]

I fixed the particular case of not being able to disable extensions in #3392

[FliegendeWurst]

This is fixed now that #3392 is merged