drop the non-editor screen stubs the editor never contributes

editscreen.cpp and LoadScreen.cpp each end in an "#else //non-editor
version" branch defining EditScreenInit/Handle/Shutdown and the LoadSaveScreen
trio. jascreens.cpp defines the same six under "#ifndef JA2EDITOR", so a
non-editor build compiles both.

Nothing linked the editor copies. The map file for JA2.exe resolves all six
to JA2_Ja2:jascreens.cpp.obj, link.exe having taken the first archive that
answered and never pulled the other. lld-link pulls both and calls it what it
is: six duplicate symbols.

The two sets are not identical -- the editor Handle stubs return ERROR_SCREEN
where jascreens returns TRUE -- so this removes the copies that lose, leaving
the behaviour the linked image already had.

Editor/LoadScreen.cpp

@@ -1263,25 +1263,4 @@ BOOLEAN ExternalSaveMap(STR16 szFilename)
 	return(TRUE);
 }
 
-#else //non-editor version
-
-#include "types.h"
-#include "screenids.h"
-
-UINT32 LoadSaveScreenInit()
-{
-	return TRUE ;
-}
-
-UINT32	LoadSaveScreenHandle( )
-{
-	//If this screen ever gets set, then this is a bad thing -- endless loop
-	return ERROR_SCREEN ;
-}
-
-UINT32 LoadSaveScreenShutdown( )
-{
-	return TRUE ;
-}
-
 #endif

Editor/editscreen.cpp

@@ -4638,25 +4638,4 @@ BOOLEAN FindLight(INT32 iGridNo, INT8 bLightType, UINT8 *pubLightRadius, UINT8 *
 	return(FALSE);
 }
 
-#else //non-editor version
-
-#include "types.h"
-#include "screenids.h"
-
-UINT32 EditScreenInit()
-{
-	return TRUE ;
-}
-
-UINT32	EditScreenHandle( )
-{
-	//If this screen ever gets set, then this is a bad thing -- endless loop
-	return ERROR_SCREEN ;
-}
-
-UINT32 EditScreenShutdown( )
-{
-	return TRUE ;
-}
-
 #endif