When connecting a model to the TableModel class, it would connect
clicking on an item to the remove() slot of the model.
This breaks the program flow implied by the undo code:
Ui --> Undo-Command --> Model --> UI
Moreover, the naming of the remove() slot is illogical, because
clicks can also have different effects, as for example in the
cylinder-table.
Therefore, move the connect() call from TableModel to the
callers. In the case of TabDiveSite, move the remove() function
from the model to the TabWidget, where it makes more sense.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>