The plan is to simplify the visibility-control of non-interactive
chart features. As a first step identify those features that
depend on preferences-flags and factor out the setting of their
visibility into a new function updateVisibility().
This commit effectively only reorders the setting of the
visibility and therefore should have not user-visible effect.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>