Add core classes.

Claunia.Localization.Core/Plural.cs

@@ -0,0 +1,40 @@
+using System;
+
+namespace Claunia.Localization.Core
+{
+    /// <summary>
+    ///     Contains the plural forms of a string
+    /// </summary>
+    public class Plural
+    {
+        int                   items;
+        internal EventHandler Modified;
+        string                text;
+
+        /// <summary>
+        ///     Minimum number (inclusive) of items named to use this plural form
+        /// </summary>
+        public int Items
+        {
+            get => items;
+            set
+            {
+                items = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <summary>
+        ///     Plural form of the string
+        /// </summary>
+        public string Text
+        {
+            get => text;
+            set
+            {
+                text = value;
+                Modified?.Invoke(this, EventArgs.Empty);
+            }
+        }
+    }
+}