Add major and minor grid lines to the charts

[olekscode]

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It is very important to control the following:

chart gridLines.
chart horizontalGridLines.
chart verticalGridLines.

chart majorGridLines.
chart majorHorizontalGridLines.
chart majorVerticalGridLines.

chart minorGridLines.
chart minorHorizontalGridLines.
chart minorVerticalGridLines.

Some examples:

More examples: https://r-charts.com/es/ggplot2/grid/

[akevalion]

moved to pharo-graphics/Roassal