--- Copies a region to another location, potentially overwriting the exiting region.
-- @param source_pos1 Vector3 pos1 of the source region to copy.
-- @param source_pos2 Vector3 pos2 of the source region to copy.
-- @param target_pos1 Vector3 pos1 of the target region to copy to.
-- @param target_pos2 Vector3 pos2 of the target region to copy to.
-- @param airapply=false bool Whether to only replace target nodes that are air-like, leaving those that are not air-like. If false, then all target nodes are replaced regardless of whether they are air-like nodes or not.
-- @returns bool,numbers 1. Whether the copy operation was successful or not
-- z y x is the preferred loop order (because CPU cache, since then we're iterating linearly through the data array backwards. This only holds true for little-endian machines however)