Add toString methods

src/main/java/de/ailis/usb4java/topology/Usb4JavaConfiguration.java

@@ -235,4 +235,14 @@ public final class Usb4JavaConfiguration implements UsbConfiguration
         if (iConfiguration == 0) return null;
         return this.device.getString(iConfiguration);
     }
+
+    /**
+     * @see java.lang.Object#toString()
+     */
+    @Override
+    public String toString()
+    {
+        return String.format("USB configuration %02x",
+            this.descriptor.bConfigurationValue());
+    }
 }

src/main/java/de/ailis/usb4java/topology/Usb4JavaEndpoint.java

@@ -89,4 +89,14 @@ public final class Usb4JavaEndpoint implements UsbEndpoint
     {
         return this.pipe;
     }
+    
+    /**
+     * @see java.lang.Object#toString()
+     */
+    @Override
+    public String toString()
+    {
+        return String.format("USB endpoint %02x", 
+            this.descriptor.bEndpointAddress());
+    }
 }

src/main/java/de/ailis/usb4java/topology/Usb4JavaInterface.java

@@ -295,4 +295,14 @@ public final class Usb4JavaInterface implements UsbInterface
         if (iInterface == 0) return null;
         return this.configuration.getUsbDevice().getString(iInterface);
     }
+        
+    /**
+     * @see java.lang.Object#toString()
+     */
+    @Override
+    public String toString()
+    {
+        return String.format("USB interface %02x", 
+            this.descriptor.bInterfaceNumber());
+    }    
 }

src/main/java/de/ailis/usb4java/topology/Usb4JavaPipe.java

@@ -340,4 +340,14 @@ public final class Usb4JavaPipe implements UsbPipe
             this.listeners.dataEventOccurred(new UsbPipeDataEvent(this, irp));
         }
     }
+    
+    /**
+     * @see java.lang.Object#toString()
+     */
+    @Override
+    public String toString()
+    {
+        return String.format("USB pipe of endpoint %02x",
+            this.endpoint.getUsbEndpointDescriptor().bEndpointAddress());
+    }
 }

src/main/java/de/ailis/usb4java/topology/VirtualRootHub.java

@@ -341,4 +341,14 @@ public final class VirtualRootHub implements UsbHub,
     {
         this.ports.disconnectUsbDevice(device);
     }
+
+    /**
+     * @see java.lang.Object#toString()
+     */
+    @Override
+    public String toString()
+    {
+        return this.getManufacturerString() + " " + this.getProductString() + 
+            " " + this.getSerialNumberString();
+    }
 }