* Improve debugging in message classes Each PowermaxBaseMessage subclass had its own toString() which added useful debug info but duplicated a lot of the logic in the message handler. I've moved the debug info inline and removed the duplication, and also added decoding for more values to the debug output. * Fix for 0xFF byte values, which convert to int -1 Signed-off-by: Ron Isaacson <isaacson.ron@gmail.com>