drupal 的 charts_graphs 需要的库文件(可能只需要其中一个吧)

-- SUPPORT CHARTING LIBRARIES --

* amCharts <http://www.amcharts.com/> - Commercial / Free with an ad link

* Bluff <http://bluff.jcoglan.com/> - Beautiful Graphics in Javascript - MIT and
  GPL license

* Google Charts <http://code.google.com/apis/charttools/index.html> - Is free to
  use. Google ask you to contact them if you plan on producing more than 250,000
  API calls per day, see Google Chart Usage Policy at
  <http://code.google.com/apis/chart/docs/making_charts.html>.

* Open Flash Chart 2 <http://teethgrinder.co.uk/open-flash-chart-2/> - LGPL
  license