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"