Naming fix: "viewWindowMin" should be just "min". Same for "max"

View
https://developers.google.com/chart/interactive/docs/gallery/areachart
hAxis.viewWindow.min

Added support for formatting at a cell level

Added support for formatting at a cell level, using “v”, “f” and “p”
parameters, in this order.
Example:
$chart->addRow(array(2015, new DataCell(0.8,'80%')));

Fixed ColumnChart

Fixes blank page issues brought to my attention by mpociot.

Add support for "relative" stacked Column Chart

Add support for relative stacked columns.

Added isHtml boolean to Tooltip config options

Thank you Ahmet Koca for finding this bug.

Added missing "isStacked" option

adding gitter badge