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/dMission/Mission.cpp

@@ -17,6 +17,7 @@
 #include "dServer.h"
 #include "dZoneManager.h"
 #include "InventoryComponent.h"
+#include "User.h"
 #include "Database.h"
 #include "WorldConfig.h"
 

dGame/dMission/Mission.h

@@ -13,6 +13,10 @@
 #include "MissionState.h"
 #include "MissionLockState.h"
 
+namespace tinyxml2 {
+	class XMLElement;
+};
+
 class MissionComponent;
 
 /**
@@ -223,7 +227,7 @@ public:
 
 	/**
 	 * @brief Returns the unique mission order ID
-	 * 
+	 *
 	 * @return The unique order ID
 	 */
 	uint32_t GetUniqueMissionOrderID() { return m_UniqueMissionID; };