R1881 patch for drag&drop copy

Issues fixed:
 - Crash if ctrl+shift+click on places that have no component.
 - Ctrl+shift+drag won't work on a selected component that has sub graph items ( such as a voltmeter ).
 - If I forget to clear other selections before copy a item that's unselected, it and all the selected before will get copied.

Thank you.
Patch applied at Rev 1884.