tests/test-gendoc-sv.t

color: move 'write' logic to the core ui class

One more step, the support for writing color is not directly in core. No
behavior change for the default case ('_colormode' = None).

Here are the details of what we have to change to the core method:

 * apply to 'self.label' to input in the buffered case
 * dispatch to 'win32print' when applicable
 * apply to 'self.label' to input when applicable

#require docutils gettext

  $ $TESTDIR/check-gendoc sv
  checking for parse errors