Hi,

This PR modifies 2 lines of plot.pedigree(), fixing a minor bug affecting the vertical scaling. The problem is most visible when plotting small pedigrees with multiline labels:

library(kinship2, quietly = TRUE)

# Simple trio with multiline labels
x = pedigree(1:3, dadid = c(0,0,1), momid = c(0,0,2), sex = c(1,2,1))
id = c("1", "2", "3\n1/1\n1/1\n1/1\n1/1\n1/1\n1/1")

# Plot
par(mar = c(2,2,2,2))
plot(x, id = id)

# Show plot region
box("figure")
box("plot", lty = 2)    

^{Created on 2022-09-15 with reprex v2.0.2}

As seen, the symbols are vertically squished, and the pedigree does not fill the plot region. This is caused by the following line in the source code, where the usr parameter is set:

Furthermore, I believe that vscale is slightly miscalculated:

As I understand it, the term stemp2/2 (both here and in the usr vector) is meant to account for the vertical gap between the symbol and the label. But this gap is actually stemp2 * 0.7 (i.e., labh * 0.7 after scaling):

Thus, the factor 1/2 is too small, sometimes allowing the label to go below the plot region. I suggest to simply remove it, which ensures a tiny amount of white space below the label.

Here is the same example plotted with the suggested changes:

devtools::install_github("magnusdv/kinship2", ref = "fix-scaling", quiet = TRUE)
library(kinship2, quietly = TRUE)

plot(x, id = id)

# Show plot region
box("figure")
box("plot", lty = 2)    

^{Created on 2022-09-15 with reprex v2.0.2}

Thanks for maintaining this useful package!
Magnus