- Implemented OLOO - Object linked to another object with the helper object
- added .groupBy() support
- added .stackBy() support
- added .tip() support
- added .legend() support
- added ._drawGroupByXAxis()
- added ._drawGroupByYAxis()
- added ._drawStackByXAxis()
- added ._drawStackByYAxis()
- added mouseover, mouseout, click
- use of .hasOwnProperty() to verify properties
- vm_config.data.mouseover => vm._config.mouseover
- vm_config.data.mouseout => vm._config.mouseout
- vm_config.data.click => vm._config.click
- vm_config.bars.quantiles => vm._config.quantiles
- removed class 'tip-treemap'
- vm._axes = {};
- Bars.prototype.end