Warning fixes and some minor changes here and there

- Added GetAchievementPoints to AchievementMgr

src/server/game/Handlers/GuildHandler.cpp

@@ -787,7 +787,7 @@ void WorldSession::HandleGuildRewardsQueryOpcode(WorldPacket& recvPacket)
 {
     recvPacket.read_skip<uint32>(); // Unk
 
-    if (Guild* guild = sGuildMgr->GetGuildById(_player->GetGuildId()))
+    if (sGuildMgr->GetGuildById(_player->GetGuildId()))
     {
         std::vector<GuildReward> const& rewards = sGuildMgr->GetGuildRewards();