Implemented a basic NIO socket channel interface. Non-blocking socket channels

and server socket channels are implemented.  This version works but only when
libnative is linked with g++ (because of C++ object creation code that fails
without this linking)

classpath/java/nio/channels/Channel.java

@@ -0,0 +1,8 @@
+package java.nio.channels;
+
+import java.io.IOException;
+
+public interface Channel {
+  public void close() throws IOException;
+  public boolean isOpen();
+}