color: add multiple messages input support to 'win32print' All other function doing writes support any number of input message. For simplicity, we make 'win32print' able to do the same.

color: clarify name of an argument of 'win32print' In the current code, the function called to write happens to the 'orig' version of the method calling 'win32print' (obtained with a 'super' call). However, the variable could have a better name. That will be useful when we'll stop having inheritance in play.

color: move the 'colorlabel' call to the core 'ui' class This bring us closer to supporting color in core natively. Core already have a 'label' method that was a no-op. We update its to call the new 'colorlabel' function. Behavior is unchanged when colormode = None.