Fixes issue #7.  also bug fix with split net having proper groupId now.
issue #7 (Moving track from pads then undoing doesn't work) was actually
working except the 'undo' copied over the 'hideFlag' state of true, which
meant it was moved back, but hidden.  Twiddling with the hideFlag
state before and after issuing the 'moveGroup' operation made sure
the flag got copied onto the saved state 'opHistory' list.