* For the doodad tool: skip the assets embed folder, the doodad binary doesn't
need to include all the game's doodads/levelpacks/etc. and can save on file
size.
* In `doodad resave`, .doodad files with Vacuum() and upgrade their chunker from
the MapAccessor to the RLEAccessor.
* Fix a rare concurrent map read/write error in OptimizeChunkerAccessors.
