Alignment and scale of DiveTextItems are never changed. Therefore,
pass them at construction time. This makes things much easier
if we want to cache the rendered text [currently the text is
rerendered at every paint() event].
This also removes the "parent=0" default parameter of the
constructor, because inadvertently leaving out the last argument
led to a subtle bug.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>