Undeprecate deregister() and chanelUnregistered()

Motivation:

As discussed in #2250, it will become much less complicated to implement
deregistration and reregistration of a channel once #2250 is resolved.
Therefore, there's no need to deprecate deregister() and
channelUnregistered().

Modification:

- Undeprecate deregister() and channelUnregistered()
- Remove SuppressWarnings annotations where applicable

Result:

We (including @jakobbuchgraber) are now ready to play with #2250 at
master

handler/src/main/java/io/netty/handler/ssl/SslHandler.java

@@ -43,7 +43,6 @@ import javax.net.ssl.SSLEngineResult.HandshakeStatus;
 import javax.net.ssl.SSLEngineResult.Status;
 import javax.net.ssl.SSLException;
 import java.io.IOException;
-import java.net.SocketAddress;
 import java.nio.ByteBuffer;
 import java.nio.channels.ClosedChannelException;
 import java.nio.channels.DatagramChannel;
@@ -332,17 +331,6 @@ public class SslHandler extends ByteToMessageDecoder {
         }
     }
 
-    @Override
-    public void bind(ChannelHandlerContext ctx, SocketAddress localAddress, ChannelPromise promise) throws Exception {
-        ctx.bind(localAddress, promise);
-    }
-
-    @Override
-    public void connect(ChannelHandlerContext ctx, SocketAddress remoteAddress, SocketAddress localAddress,
-                        ChannelPromise promise) throws Exception {
-        ctx.connect(remoteAddress, localAddress, promise);
-    }
-
     @Override
     public void disconnect(final ChannelHandlerContext ctx,
                            final ChannelPromise promise) throws Exception {
@@ -355,11 +343,6 @@ public class SslHandler extends ByteToMessageDecoder {
         closeOutboundAndChannel(ctx, promise, false);
     }
 
-    @Override
-    public void read(ChannelHandlerContext ctx) {
-        ctx.read();
-    }
-
     @Override
     public void write(final ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
         pendingUnencryptedWrites.add(PendingWrite.newInstance(msg, promise));

transport/src/main/java/io/netty/channel/group/ChannelGroup.java

@@ -214,7 +214,6 @@ public interface ChannelGroup extends Set<Channel>, Comparable<ChannelGroup> {
      * @return the {@link ChannelGroupFuture} instance that notifies when
      * the operation is done for all channels
      */
-    @Deprecated
     ChannelGroupFuture deregister();
 
     /**