Updates GraphSpace objects serialized from
previous package versions, adding any missing slots with default values.
Examples
data('gtoy1', package = 'RGraphSpace')
gs <- GraphSpace(gtoy1)
#> Validating the 'igraph' object...
#> Ignoring graph-level attributes: 'name', 'mode', 'center'
#> Creating a 'GraphSpace' object...
# Objects built with the current version are returned unchanged
gs <- updateGraphSpace(gs)