Change history of write_xlsx rubygem.
2014-11-30 v0.80.0
   Chart Data Label enhancements. Added number formatting, font handling
   (Excel::Writer::XLSX issue #106), separator (Same issue #107) and legend key.
   Added chart specific handling of data label positions since not all
   positions are available for all chart types. Excel::Writer::XLSX Issue #110.

2014-11-29 v0.79.0
   Added option to add images to headers and footers.
   Added option to not scale heaader/footer with page.
   Fixed issue where non 96dpi images weren’t scaled properly in Excel.
   Fix for issue where X axis title formula was overwritten by the
   Y axis title.

2014-11-22 v0.78.0
   Added Doughnut chart with set_rotation and set_hole_size methods.
   Added set_rotation method to Pie charts.
   Added set_calc_mode method to control automatic calculation of
   formulas when worksheet is opened.


2014-08-19 v0.77.2
   Fix for issue #16.

2014-07-02 v0.77.1
   Fix for issue #14. thanks leonid-pavlov.

2014-05-12 v0.77.0
   Fix for incorrect chart offsets in insert_chart() and set_size().

2014-04-10 v0.76.3
   dependency must be written in gemspec

2014-04-10 v0.76.2
   Fix for issue #8
   use same rubyzip routine both in ruby-2+, 1.9+ and 1.8

2014-03-21 v0.76.1
   Fix for issue #7

2014-01-31 v0.76.0
   Added date axis handling to charts.
   Added support for non-contiguous chart ranges.
   Fix to remove duplicate set_column() entries.

2013-12-09 v0.75.0
   Added interval unit option for category axes.
   Fix for axis name font rotation.
   Fix for several minor issues with Pie chart legends.

2013-11-18 v0.74.0
   Improved defined name validation.
     Allow utf8 character etc.
   Added Chart#set_title option to turn off automatic title.
   Allow positioning of plotarea, legend, title and axis names.
   Fix for modification of user params in conditional_formatting.

2013-11-13 v0.73.0
   Added custom error bar option to charts.
   Fix for tables added in non-sequential order.
   Fix for scatter charts with markers on non-marker series.
   Fix for charts with star style markers

2013-09-21 v0.72.3.beta1
   speed up when script handles large number of cells.

2013-09-07 v0.72.2
   work well with rubyzip 1.0.0

2013-09-06 v0.72.1
   specify rubyzip version : <1.0.0

2013-09-03 v0.72.0
   Fix for charts and images that cross rows and columns that are hidden or formatted but which don't have size changes.
   Fix : Worksheet#write bug when using A1 notation and blank token.

2013-09-02 v0.71.0
   Fixed issue in image handling.
   Added fix to ensure formula calculation on load regardless of Excel version.

2013-07-13 v0.70.0
   Fix for rendering images that are the same size as cell boundaries.
   Fix for inaccurate column width calculation.
   Added Chart line smoothing option.

2013-06-30 v0.69.0
   Added chart font rotation property. Mainly for use with data axes to make the display more compact.
   Fix for issue where shapes on one worksheet corrupted charts on a subsequent worksheet.
   Fix for issue where add_button invalidated cell comments in the same workbook.
   Fix for set_selection with cell range.
   Fix for issue with image scaling.

2013-03-23 v0.65.1
   Bug fix for non-integer image scaling.
   Bug fix in Worksheet#set_first_sheet
   Bug fix in Worksheet#start_page=()

2013-03-23 v0.65.0
   Added options to format series Gap/Overlap for Bar/Column charts.

   Bug fix in Worksheet#write_formula
   (write_formula change original formula string)

   Bug fix in Worksheet#set_column
   (failure when parameter level is out of range)

2013-03-06 v0.64.1
   Bug fix in handling utf-8 string under ruby 1.8.7
   (examples/demo.rb failed under ruby 1.8.7)

   fix in Worksheet#set_h_pagebreaks

2013-03-05 v0.64.0
   Added the option to format individual points in a chart series.
   This allows Pie chart segments to be formatted.


2013-03-05 v0.63.0
  Added Chart data tools such as:
    Error Bars
    Up-Down Bars
    High-Low Lines
    Drop Lines.
  See the chart_data_tools.rb example.

2013-02-24 v0.62.0
  Added option for adding a data table to a Chart X-axis.
  See output from chart_data_table.rb example.

2013-02-23 v0.61.0
  Allow a cell url string to be over written with a number or formula
  using a second write() call to the same cell. The url remains intact.

  Added Worksheet#set_default_row method to set worksheet default values
  for rows.

  Added Chart#size method to set the chart dimensions.

2013-02-19 v0.60.0
 Added Excel form buttons via the worksheet insert_button() method.
 This allows the user to tie the button to an embedded macro imported
 using add_vba_project().
 The portal to the dungeon dimensions is now fully open.

 bug fix in Worksheet#write_url
 bug fix in bin/vba_extract.rb

2013-02-17 v0.59.0
 Added macro support via VBA projects extracted from existing Excel
 xlsm files. User defined functions can be called from worksheets
 and macros can be called by the user but they cannot, currently,
 be linked to form elements such as buttons.

2013-02-10 v0.58.0
 Added chart area and plot area formatting.

2013-02-10 v0.57.0
 Add major and minor axis chart gridline formatting.

2013-02-09 v0.56.0
 Fix for issue where chart creation order had to be the same as the insertion order or charts would be out of sync.
 Fixed issue where gridlines didn't work in Scatter and Stock charts.

2013-02-09 v0.55.0
 Added Sparklines.

2013-02-07 v0.54.0
 Added font manipulation to Charts.
 Added number formats to Chart axes.
 Added Radar Charts.

2012-11-30 v0.51.0
 Impliment Shape, Table as welll as Excel::Write::XLSX-0.51

2012-02-14 v0.0.4
 Fix for x-axis major/minor units in scatter charts.(CPAN_0.46)

2012-01-25 v0.0.3
 alignment format support. see examples/formats.rb

2012-01-20 v0.0.1
 initial release