save readSplus, sp2Mondrian from maptools?

[rsbivand]

maptools::readSplus() and maptools::sp2WB() - email Andrew Lawson; see becarioprecario/DCluster#1
sp2Mondrian - Ihaka lecture by Antony Unwin 2023-09-28 https://www.youtube.com/watch?v=gggu4HVZETo