fix Issue about drag in multi trees & expandNode

Issue Info:
1.  when you drag node in multi trees, the other tree will trigger the
addHoverDom callback.
2.  when you drag node in multi trees, if 'beforeDrog' return false or
'setting.edit.drag.prev / inner / next' return false,  the source node
will not trigger addHoverDom callback
3.  When you set async.enable = true, and you use expandNode() function
to expand node,  if you set sonSign = true, you will can't see it's
child nodes.