cleanup: remove DIVE EditMode in MainTab

That mode is not used anymore, since only the editing of
profiles of manually added dives enters editing mode. For
that case we have the MANUALLY_ADDED_DIVE edit mode.

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

desktop-widgets/tab-widgets/maintab.h

@@ -28,7 +28,6 @@ class MainTab : public QTabWidget {
 public:
 	enum EditMode {
 		NONE,
-		DIVE,
 		MANUALLY_ADDED_DIVE,
 		IGNORE_MODE
 	};