Set default cell text color to white (REnamer, d347fdf)

White (or light grey) text is needed in HUD stlye windows, so change the text color to white in the table cells.

Even so, a NSTextField/NSTextFieldCell subclass will still be required, I believe, in order to suppress the unwanted blue selection highlighting.

Signed-off-by: Greg Hurrell <greg@hurrell.net>