Do not draw plot marker if the value is 0

[KleinK0910]

On the attached screenshot of an example, the first three rows have 0 (or empty) values in all years, but the markers still appear.

[simzer]

Zero height markers are drawn with zero height. They can only be seen because all markers have an 1px border on barchart by default. Setting the linewidth to 0, a the bars with 0 height disappear: https://jsfiddle.net/simzer/x63umje8/2/

[simzer]

Workaround:

  style: {
  	plot: {
      marker: {
        borderOpacityMode: 'straight',
        borderOpacity: 0
      }
    }
  }

[simzer]

First we need to handle 0 value and NaN/missing value differently.
Also what about scatterplot?