Copy and Paste of Components between nets

[Jiri Srba]

We should add to the menu two new items "Copy component" and "Paste component"
that will work across the different tabs (between different nets).

If the component name is already on the list, it should be added "Copy" after the name.

Also if some names (places/transitions) are shared, they should become shared where
it were copied (provided that the names are shared in the new net too) - this should be
automatic without the need to do anything.