Prefer C++-style over C-style type casting.
Use qApp instead of QApplication/QCoreApplication::instance().
Use explicit QString::fromLatin1()/fromUtf8() where applicable.
1. add the option the code to be used under GPLv2 or GPLv3; previously only GPLv2 was allowed
2. add the "proxy option" as described in GPLv3 so we can add future licenses without having to bulk-edit everything again :)
3. remove the awkward "exception for MIT code in Mac client" clause; it was unnecessary and confusing.
1. add "show backup trackers" togglebutton.
2. fix bug where toggling "show more" didn't take effect instantly
3. sync the "show more" preferences key with the GTK+ client
4. fix a couple of minor tracker text inconsistencies with the GTK+ client
