Remove entityclass::cleanup()

This function's sole purpose was to make sure obj.nentity was in sync,
and that obj.nentity-1 pointed to the last 'active' entity in
obj.entities. But now that obj.nentity is removed and we use
obj.entities.size() instead, it is no longer necessary.

desktop_version/src/Logic.cpp

@@ -498,8 +498,6 @@ void towerlogic()
 
 
         }
-        //now! let's clean up removed entities
-        obj.cleanup();
 
         //Looping around, room change conditions!
     }
@@ -1014,9 +1012,6 @@ void gamelogic()
             obj.entitycollisioncheck();         // Check ent v ent collisions, update states
         }
 
-        //now! let's clean up removed entities
-        obj.cleanup();
-
         //Using warplines?
         if (obj.customwarpmode) {
             //Rewritten system for mobile update: basically, the new logic is to