Avoid double construction of sector in getsector
Remove global Smap, and replace it with local smap instances.  Make makeuniv run verbose from cmake.  Pass references everywhere for sectors and sector_maps.  Pull Migrate2 into do_sector, and mark it as static.  Initialize sectors directly from the sqlite output, rather than one field at a time.  Remove Sector macro.  Rewrite grow algorithm.  We no longer make copies over and over of the sector map - we disallow copies with the new structure and the sectors - instead we create a worklist and then execute it on the map.  Define empty constructor for sector, needed for initializing inital sectors which are pieced together.  Add maxy_ to sector, allowing us to avoid passing planet all over the place as well.  When building asteroids, avoid buffer overrun when selecting some sectors to be land.