dGame Precompiled header improvements (#876)

* moving branch

* Add deleteinven slash command

* Change name of BRICKS_IN_BBB

* Use string_view instead of strcmp

* Clean up include tree

* Remove unneeded headers from PCH files

Removes unneeded headers from pre-compiled headers.  This increases compile time, however reduces development time for most files.

* Update Entity.h

* Update EntityManager.h

* Update GameMessages.cpp

* There it compiles now

Co-authored-by: Aaron Kimbrell <aronwk.aaron@gmail.com>

dGame/EntityManager.h

@@ -2,15 +2,17 @@
 #define ENTITYMANAGER_H
 
 #include "dCommonVars.h"
-#include "../thirdparty/raknet/Source/Replica.h"
 #include <map>
 #include <stack>
-
-#include "Entity.h"
 #include <vector>
+#include <unordered_map>
+
+class Entity;
+class EntityInfo;
+class Player;
+class User;
 
 struct SystemAddress;
-class User;
 
 class EntityManager {
 public: