Kdb import merge

Brings the merging framework to the import command. I commented all the side_value tests because i couldn't find this value in any testdata. 
Ok, I think I understood it now, but is there any efficient way to cut below a certain parentKey and retrieve the surrounding KeySet (i.e. not the result of the cut operation as now, but the complement of the cutted keys)?

Also, how could I test this behaviour? I didn't even notice unexpected results.