- instead of creating new QSettings objects whenever we want to
save some data, we are using global QSettings object that is
keeping its data in memory and writing to disk only when
really needed
- Faenza icons are no longer explicitly shown in prefereneces and site
info
- they are now used only if icon is not found in active theme, and also
for Windows users
- please test it and let me know if icons are correct for each category
- also fixes previous commit