Added the informal address to the BeyondFacts Lab (#1176)

app/MindWork AI Studio/Tools/PluginSystem/I18N.cs

@@ -1,5 +1,7 @@
 using System.Globalization;
 
+using AIStudio.Settings.DataModel;
+
 namespace AIStudio.Tools.PluginSystem;
 
 public class I18N : ILang
@@ -28,12 +30,51 @@ public class I18N : ILang
     /// </remarks>
     public CultureInfo Culture { get; private set; } = CultureInfo.InvariantCulture;
 
+    /// <summary>
+    /// Asks where the form of address comes from, see AddressForm.
+    /// </summary>
+    private Func<AddressForm> addressFormSource = () => AddressForm.FORMAL;
+
+    /// <summary>
+    /// How the texts of TA() address the person, in languages which tell a formal address from an informal one.
+    /// </summary>
+    /// <remarks>
+    /// Like the language, it holds for every text, so that a static class, such as one with the labels of an enum,
+    /// addresses the person the same way as a component does. Only texts of TA() have an informal variant; all
+    /// other texts stay formal. Program.cs decides where the choice comes from, see UseAddressFormOf.
+    /// </remarks>
+    public AddressForm AddressForm => this.addressFormSource();
+
     public static void Init(ILanguagePlugin language)
     {
         I.language = language;
         I.Culture = CommonTools.DeriveActiveCultureOrInvariant(language.IETFTag);
     }
 
+    /// <summary>
+    /// Sets where the form of address comes from.
+    /// </summary>
+    /// <remarks>
+    /// The source is asked for every text, so a changed setting shows as soon as a component renders again.
+    /// </remarks>
+    /// <param name="source">Gets the form of address the person chose.</param>
+    public static void UseAddressFormOf(Func<AddressForm> source) => I.addressFormSource = source;
+
+    /// <summary>
+    /// Gets a text which addresses the reader, in the form of address the person chose; see AddressForm.
+    /// </summary>
+    /// <param name="fallbackEN">The text in English (US).</param>
+    /// <param name="typeNamespace">The namespace of the type requesting the text, used as part of the key.</param>
+    /// <param name="typeName">The name of the type requesting the text, used as part of the key.</param>
+    /// <returns>The text from the language plugin or the English text.</returns>
+    public string TA(string fallbackEN, string? typeNamespace, string? typeName)
+    {
+        if(this.language is not null)
+            return this.GetText(this.language, fallbackEN, typeNamespace, typeName, this.AddressForm);
+
+        return fallbackEN;
+    }
+
     #region Implementation of ILang
 
     public string T(string fallbackEN)