Remove uppertopology in GModel, reverting commit a while ago (not necessary...

Remove uppertopology in GModel, reverting commit a while ago (not necessary anymore). Draw commands are piped to mesh for compounds now, so DiscreteSurfaces should work without showCompounds option enabled. Without showCompounds enabled, compounded surfaces/edges are hidden from the user, making only the uppermost topology part accessible. Selections of lower surfaces are piped to the compound.