Add CW keying, function key messages and the documentation

The function keys send through cwdaemon or a WinKeyer, with N1MM's message
macros. Escape stops sending.

Settings are read with the reflection serializer rather than a generated one:
the generated one hands back null for every property the file leaves out
instead of the value the property is declared with, which crashed the program
the first time a new setting was added.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/Nonemm.Keying.Tests/CwDaemonSenderTests.cs

@@ -0,0 +1,52 @@
+using System.Net;
+using System.Net.Sockets;
+using System.Text;
+
+namespace Nonemm.Keying.Tests;
+
+/// The sender is tested against a socket that speaks cwdaemon's side of the
+/// protocol, so what goes on the wire is what is asserted.
+public class CwDaemonSenderTests : IDisposable
+{
+    private readonly UdpClient daemon = new(new IPEndPoint(IPAddress.Loopback, 0));
+
+    private int Port => ((IPEndPoint)daemon.Client.LocalEndPoint!).Port;
+
+    public void Dispose()
+    {
+        daemon.Dispose();
+        GC.SuppressFinalize(this);
+    }
+
+    private async Task<byte[]> NextDatagram(Func<Task> send)
+    {
+        Task<UdpReceiveResult> receiving = daemon.ReceiveAsync();
+        await send();
+        UdpReceiveResult received = await receiving.WaitAsync(TimeSpan.FromSeconds(5));
+        return received.Buffer;
+    }
+
+    [Fact]
+    public async Task TextGoesOutInUpperCase()
+    {
+        using CwDaemonSender sender = new("127.0.0.1", Port);
+        byte[] sent = await NextDatagram(() => sender.SendAsync("cq test de dl1abc"));
+        Assert.Equal("CQ TEST DE DL1ABC", Encoding.ASCII.GetString(sent));
+    }
+
+    [Fact]
+    public async Task AbortIsTheEscapeFourCommand()
+    {
+        using CwDaemonSender sender = new("127.0.0.1", Port);
+        byte[] sent = await NextDatagram(() => sender.AbortAsync());
+        Assert.Equal([0x1B, (byte)'4'], sent);
+    }
+
+    [Fact]
+    public async Task SpeedIsTheEscapeTwoCommand()
+    {
+        using CwDaemonSender sender = new("127.0.0.1", Port);
+        byte[] sent = await NextDatagram(() => sender.SetSpeedAsync(32));
+        Assert.Equal([0x1B, (byte)'2', (byte)'3', (byte)'2'], sent);
+    }
+}