Undo: return number of changed dives from undo commands

To enable a "multiple dives edited" message, return the number
of edited dives from dive edit undo commands. Since there are
two kinds of these commands, viz. normal fields and tag fields,
and the former use templates, create a common base class that
can return the number of dives. Yes, the class hierarchy is
getting scarily deep! At least, this gives a tiny bit of
code-reuse.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

0 files changed, 0 insertions, 0 deletions