Use const ref to avoid copies

src/blackmisc/db/artifactlist.cpp

@@ -194,7 +194,7 @@ namespace BlackMisc
         qint64 CArtifactList::getTotalFileSize() const
         {
             qint64 s = 0;
-            for (const CArtifact a : *this)
+            for (const CArtifact &a : *this)
             {
                 s += a.getFileSize();
             }

src/blackmisc/network/user.cpp

@@ -166,7 +166,7 @@ namespace BlackMisc
 
             int uc = 0;
             int lc = 0;
-            for (const QChar ch : realName)
+            for (const QChar &ch : realName)
             {
                 // Joe Doe -> valid
                 // jOE dOE -> invalid