replace v6 with experimental v7 code

src/MpvNet/Global.cs

@@ -0,0 +1,11 @@
+
+namespace MpvNet;
+
+public static class Global
+{
+    public static readonly string BR = Environment.NewLine;
+    public static readonly string BR2 = Environment.NewLine + Environment.NewLine;
+    public static readonly MainPlayer Player = new MainPlayer();
+    public static readonly MainPlayer Core = Player; // backward compatibility
+    public static readonly AppClass App = new AppClass();
+}