minor issue: superimposed mexes

[phongu]

on neroxis_map_generator_1.6.9_f5g26mkcspivu_baeaeasfceraotc5baka_
spanws on the SW-NE diagonal feature 2 mexes almost on top of each other. each appears to be part of a cluster of mexes as you usually see at commander spawn points or expansions, but it looks like the clusters overlap.