To this end, two new ChartItems were added: A "bar" (a rectangle
with a border) and a "text" (multiple lines of text).
It turns out that the text on the bars now looks atrocious.
The reason appears to be that the antialiasing of the font-rendering
does not blend into the alpha channel, but into a supposed
background color? This will have to be investigated.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>