This PR fixes some C4996 deprecation warnings.
cc: @jcfr
warning C4996: 'fileno': The POSIX name for this item is deprecated. Instead, use the ISO C and C++ conformant name: _fileno. See online help for details.
warning C4996: 'QList<QString>::toSet': Use QSet<T>(list.begin(), list.end()) instead.
warning C4996: 'QString::SkipEmptyParts': was declared deprecated
warning C4996: 'QString::split': Use Qt::SplitBehavior variant instead
warning C4996: 'QSet<T>::toList': Use values() instead.
This PR fixes some C4996 deprecation warnings. cc: @jcfr