The visibility of axis text / lines is never changed, so set
in axis constructor.
Moreover, instead of rendering the lines/text and then setting
them invisible, do not render them if invisible.
The whole thing appears superfluous, since the proper way to
not show lines/text is to just not call updateTicks on the
axis. But in the future we might want to have axes with text
but no lines, so keep for now.
Since this means breaking out the text / line rendering
into their own function, we might rename some variables to
make them (at least somewhat) more clear.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
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