Remove old C# callback code

ports/csharp/csharp_callback.cs

@@ -1,255 +0,0 @@
-using System.Runtime.InteropServices;
-
-public struct CallbackMessage
-{
-    public int eventCode;
-    /* Pointers to structures that contain details about the 
-    subject of the callback */
-    public System.IntPtr node;
-    public System.IntPtr network;
-    public System.IntPtr netif;
-    public System.IntPtr route;
-    public System.IntPtr path;
-    public System.IntPtr peer;
-    public System.IntPtr addr;
-}
-
-[StructLayout(LayoutKind.Sequential)]
-public struct SockAddrStorage
-{
-    public byte Length;
-    public byte Family;
-    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
-    public byte[] Data1;
-    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
-    public uint[] Data2;
-    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
-    public uint[] Data3;
-}
-
-[StructLayout(LayoutKind.Sequential)]
-public struct SockAddr
-{
-    public ushort Family;
-    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 14)]
-    public byte[] Data;
-}
-
-[StructLayout(LayoutKind.Sequential)]
-public struct SockAddrIn
-{
-    public byte Length;
-    public byte Family;
-    public ushort Port;
-    public uint Addr;
-    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
-    public byte[] Zero;
-}
-
-public struct NodeDetails
-{
-    /**
-	 * The node ID
-	 */
-    public ulong address;
-
-    /**
-	 * The current clock value accord to the node
-	 */
-    public ulong clock;
-
-    /**
-	 * Whether or not this node is online
-	 */
-    public bool online;
-
-    /**
-	 * Whether port mapping is enabled
-	 */
-    public bool portMappingEnabled;
-
-    /**
-	 * Whether multipath support is enabled. If true, this node will
-	 * be capable of utilizing multiple physical links simultaneosly
-	 * to create higher quality or more robust aggregate links.
-	 *
-	 * See: https://www.zerotier.com/manual.shtml#2_1_5
-	 */
-    public bool multipathEnabled;
-
-    /**
-	 * The port used by the service to send and receive
-	 * all encapsulated traffic
-	 */
-    public ushort primaryPort;
-
-    /**
-	 * Planet ID
-	 */
-    public ulong planetWorldId;
-    public ulong planetWorldTimestamp;
-    public byte versionMajor;
-    public byte versionMinor;
-    public byte versionRev;
-};
-struct AddrDetails
-{
-    public ulong nwid;
-    public SockAddrStorage addr;
-};
-
-struct NetifDetails
-{
-    /**
-	 * The virtual network that this interface was commissioned for.
-	 */
-    public ulong nwid;
-
-    /**
-	 * The hardware address assigned to this interface
-	 */
-    public ulong mac;
-
-    /**
-	 * The MTU for this interface
-	 */
-    public int mtu;
-};
-
-struct RouteDetails
-{
-    /**
-	 * Target network / netmask bits (in port field) or NULL or 0.0.0.0/0 for default
-	 */
-    public System.IntPtr target;
-
-    /**
-	 * Gateway IP address (port ignored) or NULL (family == 0) for LAN-local (no gateway)
-	 */
-    public System.IntPtr via;
-
-	/**
-	 * Route flags
-	 */
-	public ushort flags;
-
-    /**
-	 * Route metric (not currently used)
-	 */
-    public ushort metric;
-};
-
-struct NetworkDetails
-{
-    /**
-	 * Network ID
-	 */
-    public ulong nwid;
-
-    /**
-	 * Maximum Transmission Unit size for this network
-	 */
-    public int mtu;
-
-    /**
-	 * Number of addresses (actually) assigned to the node on this network
-	 */
-    public short num_addresses;
-
-    /**
-	 * Array of IPv4 and IPv6 addresses assigned to the node on this network
-	 */
-    [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 16)]
-    public System.IntPtr[] addr;
-
-    /**
-	 * Number of routes
-	 */
-    public uint num_routes;
-
-    /**
-	 * Array of IPv4 and IPv6 addresses assigned to the node on this network
-	 */
-    [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 32)]
-    public System.IntPtr[] routes;
-};
-
-struct PathDetails
-{
-    /**
-	 * Address of endpoint
-	 */
-    public System.IntPtr address;
-
-	/**
-	 * Time of last send in milliseconds or 0 for never
-	 */
-	public ulong lastSend;
-
-    /**
-	 * Time of last receive in milliseconds or 0 for never
-	 */
-    public ulong lastReceive;
-
-    /**
-	 * Is this a trusted path? If so this will be its nonzero ID.
-	 */
-    public ulong trustedPathId;
-
-    /**
-	 * Is path expired?
-	 */
-    int expired;
-
-    /**
-	 * Is path preferred?
-	 */
-    int preferred;
-};
-
-struct PeerDetails
-{
-    /**
-	 * ZeroTier address (40 bits)
-	 */
-    public ulong address;
-
-    /**
-	 * Remote major version or -1 if not known
-	 */
-    int versionMajor;
-
-    /**
-	 * Remote minor version or -1 if not known
-	 */
-    int versionMinor;
-
-    /**
-	 * Remote revision or -1 if not known
-	 */
-    int versionRev;
-
-    /**
-	 * Last measured latency in milliseconds or -1 if unknown
-	 */
-    int latency;
-
-    /**
-	 * What trust hierarchy role does this device have?
-	 */
-    public int role;
-
-	/**
-	 * Number of paths (size of paths[])
-	 */
-	public uint pathCount;
-
-    /**
-	 * Known network paths to peer
-	 */
-    [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 16)]
-    public System.IntPtr[] paths;
-};
-
-[UnmanagedFunctionPointerAttribute(CallingConvention.Cdecl)]
-public delegate void CSharpCallback(System.IntPtr msg);