[refactor] Remove the word 'Manager' from most source files/namespaces

ChatManager -> Chat
MissionManager -> Missions
NanoManager -> Nanos
TransportManager -> Transport
ChunkManager -> Chunking
BuddyManager -> Buddies
GroupManager -> Groups
RacingManager -> Racing
ItemManager -> Items

NPCManager and PlayerManager remain.

Note: You can use git log --follow src/file.cpp to trace the history of
a file from before it was renamed.

src/Groups.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "Player.hpp"
+#include "CNProtocol.hpp"
+#include "CNStructs.hpp"
+#include "CNShardServer.hpp"
+
+#include <map>
+#include <list>
+
+namespace Groups {
+	void init();
+
+    void sendToGroup(Player* plr, void* buf, uint32_t type, size_t size);
+    void groupTickInfo(Player* plr);
+    void groupKickPlayer(Player* plr);
+    int getGroupFlags(Player* plr);
+}