undo: more fine-grained undo of profile editing

Place undo commands for every change of the profile, not
only on "saving". Move the edit-mode from the mainwindow
and the maintab to the profile widget.

This is still very rough. For example, the only way to exit
the edit mode is changing the current dive.

The undo-commands are placed by the desktop-profile widget.
We might think about moving that down to the profile-view so
that this will be useable on mobile.

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

commands/command_base.cpp

@@ -80,7 +80,6 @@ QString getListOfDives(QVector<struct dive *> dives)
 	return getListOfDives(std::vector<struct dive *>(dives.begin(), dives.end()));
 }
 
-
 // return a string that can be used for the commit message and should list the changes that
 // were made to the dive list
 QString changesMade()