The function creates a plot of the landmark coordinates for all specimens. This is useful for examining
patterns of variation in Procrustes shape variables, after a GPA has been performed. If "mean = TRUE", the mean shape will be calculated and added to the plot.
Additionally, if a matrix of links is provided, the landmarks of the mean shape will be connected by lines.
The link matrix is an m x 2 matrix, where m is the desired number of links. Each row of the link matrix
designates the two landmarks to be connected by that link. The function will plot either two- or
three-dimensional data (e.g. see define.links
).