try to fix some obvious bugs about `groups`

Hi All,
I just upgraded to 2.10 and I found some bugs immediately.
1. in the right-click-menu there is no `move-to-group` but 2 `remove
from group` instead.
2. I like the new add/remove/move panel, but the scrolling is not
working, which is a big problem. Because I have lots of groups which
cannot even fit into the full screen height after expansion.
3. no way to expand or collapse all nodes

I tried the dev version, all problems still exist. Here is my fixation.

Cheers,

W.L.