The symbols previously used were a Canadian script, and were looking good enough, but they might not be installed in every machine. Besides, all this is to workaround a Qt5 bug that prevents from rendering those symbols at times.
git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@261 014f5005-505e-4b48-8d0a-63407b615a7c