Fix the nick colour plugin.

nickcolours/src/com/dmdirc/addons/nickcolours/NickColourInputDialog.java

                 nickname.getText().toLowerCase(),
                 new Color(colour.getRed(), colour.getGreen(), colour.getBlue()));
         if (isnew) {
-            model.replaceValueAt(entry, row);
-        } else {
             model.addValue(entry);
+        } else {
+            model.replaceValueAt(entry, row);
         }
     }
 

nickcolours/src/com/dmdirc/addons/nickcolours/NickColourUtils.java

     }
 
     static String getStringFromColor(final Color color) {
+        if (color == null) {
+            return "";
+        }
         return ColourUtils.getHex(new Colour(color.getRed(), color.getGreen(), color.getBlue()));
     }