Changed purge level of all map thinkers to PU_MAP (was a mixture of PU_MAP and PU_MAPSPEC) as AFAIC, there is no need to separate them, as we'd only ever want to purge them together (or free manually when necessary/desired). Removed unused/unnecessary zone memory purge levels; PU_MAPSPEC/PU_DAVE/PU_OPENGL.
Changed purge level of all map thinkers to PU_MAP (was a mixture of PU_MAP and PU_MAPSPEC) as AFAIC, there is no need to separate them, as we'd only ever want to purge them together (or free manually when necessary/desired). Removed unused/unnecessary zone memory purge levels; PU_MAPSPEC/PU_DAVE/PU_OPENGL.