v1.0.0

• Support for two new colour spaces has been added: LMS, a direct
  representation of the response levels of each of the three colour receptor
  types in the eye; and LCh, a polar representation of Lab space.
• The new dichromat() function can be used to simulate colour blindness.
• The gradient() function now additionally supports predefined colour maps from
  matplotlib and ColorBrewer. Its second argument is now interpreted a little
  differently.
• The hueshift() function has been removed, in favour of the more general
  combination of hue() and delta(). hue(x, delta(y)) is the equivalent of the
  old hueshift(x,y), and delta() can also be used with other colour properties.
• New colour property functions lightness() and chroma() have been added.
• Dimensions are now set when two or more colour properties are changed, and
  the swatch() visualisation function plots multidimensional shades in a grid.
• There is now a rev() method for shades.
• The all.equal() method for shades now passes on its ellipsis argument when
  checking colour coordinates.