colors.py: attempt to fix linear interpolation for CMYKColorSep class
colors.py: attempt to fix linear interpolation for CMYKColorSep class

kanarelo/reportlab,Distrotech/reportlab,kanarelo/reportlab,kanarelo/reportlab,Distrotech/reportlab,kanarelo/reportlab,Distrotech/reportlab,kanarelo/reportlab,Distrotech/reportlab,Distrotech/reportlab