Base for 4.3 work. Split Nadeko.Common into a separate project

src/Nadeko.Common/ShmartNumber.cs

@@ -0,0 +1,40 @@
+namespace Nadeko.Common;
+
+public readonly struct ShmartNumber : IEquatable<ShmartNumber>
+{
+    public long Value { get; }
+    public string? Input { get; }
+
+    public ShmartNumber(long val, string? input = null)
+    {
+        Value = val;
+        Input = input;
+    }
+
+    public static implicit operator ShmartNumber(long num)
+        => new(num);
+
+    public static implicit operator long(ShmartNumber num)
+        => num.Value;
+
+    public static implicit operator ShmartNumber(int num)
+        => new(num);
+
+    public override string ToString()
+        => Value.ToString();
+
+    public override bool Equals(object? obj)
+        => obj is ShmartNumber sn && Equals(sn);
+
+    public bool Equals(ShmartNumber other)
+        => other.Value == Value;
+
+    public override int GetHashCode()
+        => Value.GetHashCode();
+
+    public static bool operator ==(ShmartNumber left, ShmartNumber right)
+        => left.Equals(right);
+
+    public static bool operator !=(ShmartNumber left, ShmartNumber right)
+        => !(left == right);
+}