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.
- Simplified code of optimizations module
- Improved doc of optimization module
- Added option to get all the intermediate passages of optimization
git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@269 014f5005-505e-4b48-8d0a-63407b615a7c