Update copy/cut/paste-over/insert support. You can now cut a group/lib/section

and when pasted, all the child subs/dirs/xtrns will be pasted with it.
If however, you cut a group/lib/section and then exit SCFG, you'll lose all the
children subs/dir/xtrns that were on the "clipboard" along with the parent.

Copy - F5, Ctrl-C, Ctrl-Insert
Cut - Shift-Del, Ctrl-X
Paste Over - F6, Ctrl-V
Paste Insert - Shift-Insert