Handle chart configs with multiple X axes

[AleksueiR]

need to decide how the zoom slider should behave with multiple axes

• have a single slider for all
• have a slider for each axis

[spencerwahl]

Possible thought: for multiple axes (x or y) maybe instead of restricting the view of the chart we fade out values not in the selected range.

eg. A chart has both a smoothed precipitation line and bars for temperature. You restrict the temperature slider to 0C-10C, this then fades out any bars with value < 0C or >10C and doesn't affect the view of the overall graph. Then all precipitation values can be seen against a smaller range of temperature values.