Feature request: Make scales on "plot all barcode biaxials" view in the debarcoder uniform so the plots can be more easily compared with each other

[givison]

I realized today that the scales for all the scatterplots are different when looking at the "plot all barcode biaxials" view, which makes it challenging to assess the strength of the signal on the positive channels in relation to the negative channels. I think it would be a much more useful visualization if they all had fixed scales. I wrote a small modification to the plot_all_barcode_biaxials() function in the package that fixes the scales on all the plots to be between 0-6 in arcsinh space, and it works well I assign it in my namespace before running the GUI. If you agree that it's a worthwhile feature, feel free to use the code below:

fixed_scales_plot <- function (m, bc.channels) {
    plotlist <- list()
    mahal.dist <- m[, "mahal.dist"]
    m <- m[, bc.channels]
    m <- cbind(m, mahal.dist = mahal.dist)
    m <- data.frame(m)
    for (i in 1:length(bc.channels)) for (j in 1:length(bc.channels)) {
        if (i == j) {
            plot <- (ggplot2::ggplot(ggplot2::aes_string(x = names(m)[i]), 
                                     data = m) + ggplot2::geom_histogram() + ggplot2::scale_x_continuous("") + 
                         ggplot2::scale_y_continuous("") +
                         ggplot2::expand_limits(x = c(0, 6)))
            if (i == 1) 
                plot <- plot + ggplot2::scale_y_continuous(names(m)[i])
            if (j == length(bc.channels)) 
                plot <- plot + ggplot2::scale_x_continuous(names(m)[i])
        }
        else {
            plot <- ggplot2::ggplot(ggplot2::aes_string(x = names(m)[j], 
                                                        y = names(m)[i], colour = "mahal.dist"), data = m)
            if (i > j) {
                plot <- plot + ggplot2::geom_point()
                plot <- plot + ggplot2::scale_colour_gradientn("", 
                                                               breaks = 0:30, colours = rainbow(3))
                plot <- plot + ggplot2::expand_limits(x = c(0, 6), y = c(0, 6))
            }
            else plot <- (plot + ggplot2::geom_blank() + ggplot2::theme(panel.grid.major = ggplot2::element_blank(), 
                                                                        panel.grid.minor = ggplot2::element_blank(), 
                                                                        panel.border = ggplot2::element_blank(), panel.background = ggplot2::element_blank()))
            if (j != 1) 
                plot <- plot + ggplot2::scale_y_continuous("")
            if (i != length(bc.channels)) 
                plot <- plot + ggplot2::scale_x_continuous("")
        }
        plot <- plot + ggplot2::theme(axis.line = ggplot2::element_blank(), 
                                      axis.ticks = ggplot2::element_blank(), axis.text = ggplot2::element_blank(), 
                                      legend.position = "none")
        plotlist <- c(plotlist, list(plot))
    }
    plotlist <- c(plotlist, list(nrow = length(bc.channels)))
    fun <- get("grid.arrange", asNamespace("gridExtra"))
    return(do.call(fun, plotlist))
}

assignInNamespace("plot_all_barcode_biaxials", fixed_scales_plot, "premessa")