Extensive changes to Tracer.java to allow embeddable use:

    AsyncLogger (a Logger implementation) is now available for external use;
    Tracers are to be started after instantiation;
    Loggers are serially startable and stoppable;
    Properties (Heartbeat suppression, frame decoding, and cmd body suppression)
        now modifiable until Tracer.start().

Author: Steve Powell

src/com/rabbitmq/client/impl/Frame.java

@@ -36,28 +36,22 @@
 
 /**
  * Represents an AMQP wire-protocol frame, with frame type, channel number, and payload bytes.
+ * TODO: make state private
  */
 public class Frame {
-    /**
-     * Frame type code
-     */
-    public int type;
+    /** Frame type code */
+    public final int type;
 
     /** Frame channel number, 0-65535 */
-    public int channel;
+    public final int channel;
 
     /** Frame payload bytes (for inbound frames) */
-    public byte[] payload;
-
-    /** Frame payload (for outbound frames) */
-    public ByteArrayOutputStream accumulator;
+    public final byte[] payload;
 
-    /**
-     * Constructs an uninitialized frame.
+    /** Frame payload (for outbound frames)
+     * TODO: make final; currently modified explicitly in tests.
      */
-    public Frame() {
-        // No work to do
-    }
+    public ByteArrayOutputStream accumulator;
 
     /**
      * Constructs a frame for output with a type and a channel number and a