Core/Misc: Fix some static analysis issues

Fix some static analysis issues about uninitialized values. Most of them are false positives, always initialized before being accessed, while some of them are real issues spotted by valgrind too.

src/server/game/Server/WorldSession.cpp

@@ -100,6 +100,7 @@ WorldSession::WorldSession(uint32 id, WorldSocket* sock, AccountTypes sec, uint8
     m_muteTime(mute_time),
     m_timeOutTime(0),
     AntiDOS(this),
+    m_GUIDLow(0),
     _player(NULL),
     m_Socket(sock),
     _security(sec),
@@ -122,6 +123,8 @@ WorldSession::WorldSession(uint32 id, WorldSocket* sock, AccountTypes sec, uint8
     timeLastWhoCommand(0),
     _RBACData(NULL)
 {
+    memset(m_Tutorials, 0, sizeof(m_Tutorials));
+
     if (sock)
     {
         m_Address = sock->GetRemoteAddress();