Call an undo command when editing cylinders, but only if on
the EquipmentTab.
To keep code changes small, make a copy of the cylinder first,
then edit the cylinder as before and then either call an undo
command (EquipmentTab) or overwrite the old cylinder (Planner).
The memory management here is a bit strange: Since the undo-command
itself makes a deep-copy of the passed in cylinder, we only do
a shallow copy. If we have to change the type, we allocate the
string with an std::string, so that the memory is automatically
freed at the end of the function. However, this means that in
the planner we have to make a deep copy first, swap old and
new cylinder and finally release the old cylinder. Certainly
not ideal, but for now the pragmatic thing to do.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>