CHANGES IN corrplot VERSION 0.78

NEW FEATURES

• Issue #20: Added support for Plotmath expressions. Plotmath is used if the name
  is prefixed by one of the following characters: :, = or $.

CHANGES IN corrplot VERSION 0.77

• Fixed #58, make sure the margin is correct in corrplot.mixed().
• Revised document.

CHANGES IN corrplot VERSION 0.76

• In corrplot(), added parameters na.label and na.label.col that define how NA values
  inside a matrix should be rendered.
• In corrplot(), na.label can now use one or two characters, default is "?" (issue #55)
• Fixed #17: restore par() settings on exit (thanks, @yihui)
• Fixed #16: checks for [-1, 1] interval are too strict.
• Fixed #15: error with correlation plot using insig argument when all values are significant.
• Fixed #9: added ward.D and ward.D2 hclust methods (thanks, @jeffzemla)

CHANGES IN corrplot VERSION 0.60

NEW FEATURES

• Now corrplot() can deal with the matrix not in [-1,1] by parameter zoom.
• Warning: please make sure the visualization you take after data zoom is meaningful!

CHANGES

• Function corr.rect() was renamed to corrRect().
• Revise document. (THANKS, Tao Gao)
• In function corrplot(), order's choice "PCA" was precisely renamed as "AOE".
  and "FPC" was added for the first principal component order.
• Added function corrMatOrder(), and corrplot.mixed().
• Remove seldom used functions: corrplot.circle(), corrplot.ellipse(),
  corrplot.square(), corrplot.shade(), corrplot.color(), corrplot.number().
• In corrplot(), remove parameter assign.col and cl.range,
  add zoom, cl.lim and addCoefasPercent.