Support simple arithmetic expression with df.variable or aesthetic

For example :
- `fill = change < 0` https://stackoverflow.com/questions/59989254/different-bar-color-for-positive-and-negative-bars-in-bar-plot
- `fill=factor(ifelse(area=="Południe","Highlighted","Normal"))` https://stackoverflow.com/questions/22894102/change-color-of-only-one-bar-in-ggplot
- `color=ifelse(df$y<0, 'red', 'black')` https://stackoverflow.com/questions/15804504/how-to-conditionally-highlight-points-in-ggplot2-facet-plots-mapping-color-to
- https://community.rstudio.com/t/ggplot-with-conditions/17352
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