Allow for empty cells in observation list

[DaniBodor]

Currently 0s required to indicate no extras.
would be nice if these could be omitted.
somewhere around line 528:

			// add extras
			if (currLine [2]){	// Add_#
				headers = Array.concat(headers, curr_header + "_#");
				Dialog.addToSameRow();
				Dialog.addString("#", "",1);
				out_order = Array.concat(out_order,"str");
			}