It's written ... I was looking for any mod that can dump blocks from a structure to a file (setblock) relative to a player. I'd preferred to find one than write one. Tag me, if there is any such other mod utility ? I am not looking for an editor, but a command utility for getting blocks. Updated 23 July 2016
So far it's /blockdump exfile|file|report x y z x2 y2 z2 saveto.caleb|saveto.txt <noair>
exfile creates a .caleb file for the commandrunnermod which runs files of /execute commands. Report gives a report.
Now in alpha, the Blockdumpmod is available as the companion mod for the commandrunnermod. It's another way to retrieve info from the world and place it in an another place. http://minecraft.curseforge.com/projects/commandrunnermod/files. It writes setblocks in or execute with setblocks into a .caleb file. And yes, it dumps command blocks, chests and such.
Still note that running 1000's of setblocks will be laggy. New feature is an option for noair.