[BUGFIX] Nested records are not copied right

If you copy an Row Element with nested Content Elements the information of the the column of the nested Elements is lost and the nested Elements are displayed beside the Row Element and not inside any more.

This happens because tx_flux_column of nested records is emptied as well. During my fix i encountered a few more problems with copying and moving of nested Elements and i think i found a solution for them all. 

Please check this commit! =)
I see the problem. 
We only need this lines for Cut/Paste (Move) actions.

If you move an element from inside a row element to outside the row element colPos, tx_flux_parent and tx_flux_column are never resetted.

So what about ('move' === $command) ?