Change log for Chart::Gnuplot

0.04
    - Support adding time stamp
    - Support adding arbitrary labels
    - Create temporary file when the chart object is created

0.03
    - Support financebars and candlesticks plotting styles
    - Support setting filling the boxes and candlesticks
    - Support setting style of the borders
    - Support plotting 3D graph from arrays of coordinates of data points
    - Support adding 3D data set to multiplot chart
    - Support setting of background color (experimental)
    - Support setting of plot area background color (experimental)
    - Plot in PS if the output file has no extension
    - Fix a bug of checking array lengths in error-type style
    - Update the POD

0.02
    - Fix a bug that makes converting output figure to PDF failed
    - Fix a bug that makes printing certain error mesg failed
    - Add checking whether xdata and ydata array lengths are the same
    - Add more test cases
    - Remove some redundant code

0.01
    Initial release
