featureDensity.RdPlot density of several feature tyopes across the genome
featureDensity( feature_file1 = system.file("extdata", "g4_positions.txt", package = "svBreaks"), feature1 = "G4", feature_file2 = NA, feature2 = NA, feature_file3 = NA, feature3 = NA, write = TRUE, chroms = c("2L", "2R", "3L", "3R", "X") )