Add const to many vars and arguments

Also remove const in declarations' arguments that are passed by value

src/base/bittorrent/private/bandwidthscheduler.cpp

@@ -93,7 +93,7 @@ bool BandwidthScheduler::isTimeForAlternative() const
 
 void BandwidthScheduler::onTimeout()
 {
-    bool alternative = isTimeForAlternative();
+    const bool alternative = isTimeForAlternative();
 
     if (alternative != m_lastAlternative) {
         m_lastAlternative = alternative;