BLOW CHUNKS

This is a utility that will destroy any chunk which is all air and has no Tile Entities (chests, signs, etc) and has no Entities (mobs, cows, armour stands, items, etc). Suggested by Qwertyuiopthepie

@Qwertyuiopthepie has created a tutorial here:

Select an area including the chunks you want to purge, run the filter, and save the result. You may need to reload the world (CTRL+R) to see the changes applied in MCEdit.

ALWAYS WORK WITH A BACKUP. While all care has been taken in the testing of this code, it is not using well documented APIs and you may damage your world.

v2 also purges chunks whose terrain is marked as "not populated" (i.e. the chunks around the very edge of the explored map). 

v3 suppresses re-lighting the chunks in the selection area, so the save is very quick.