Shows a legend for plot elements or their groups.
mdaplot.showLegend(legend, col, pch = NULL, lty = NULL, lwd = NULL,
bty = "o", position = "topright", plot = T)
vector with text elements for the legend items
vector with color values for the legend items
vector with marker symbols for the legend items
vector with line types for the legend items
vector with line width values for the legend items
border type for the legend
legend position ('topright', 'topleft', 'bottomright', 'bottomleft', 'top', 'bottom')
logical, show legend or just calculate and return its size