Bug fixes

• Fixed axis.y2.inner - #742
• Fixed y axis padding when data label shown - #799
• Fixed to assume axis.y.padding as pixels - #799
• Fixed to accept category name as x value for grid lines - #800
• Fixed interaction.enabled option for pie/donut/gauge chart - #801
• Fixed centered category axis - #804
• Fixed to accept unixtime string as timeseries date input - #805
• Fixed axis.y.center
• Fixed legend when revert called