Comits f427226b3b and 43c3885249f of the undo series introduced 2 calls
of autogroup_dives() without checking the autogroup global boolean.
This is a bug. An import from DC (for example) then triggers an
autogrouping, the divelist is autogrouped, and the UI button
is off.
This commit solves this. I've chosen for a guard in the autogroup_dives()
that now is a no-op when called when the user did not select autogrouping.
In additon, simplified the other calls to this function, as we do
not need to check before calling any more.
Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>