Update to allow dimensions to be expressed in other units (%, em, etc.)
Update to allow width to be set to null (fill up available width)
Allow listeners to be defined for legends
Pass listener arguments to the callback
Add the ability to set chart.exportConfig so that a chart can be exported

Required javascript files will automatically be loaded when using the amchart helper
Fix amcharts/all JS file
Bump to 3.4.7.3