(svn r27732) -Change: Turn the message about 'missing baseset sprites' from a popup into a static message that only shows in non-release versions, just like the 'missing translations' message.

src/spritecache.h

@@ -32,6 +32,7 @@ bool SpriteExists(SpriteID sprite);
 
 SpriteType GetSpriteType(SpriteID sprite);
 uint GetOriginFileSlot(SpriteID sprite);
+uint GetSpriteCountForSlot(uint file_slot, SpriteID begin, SpriteID end);
 uint GetMaxSpriteID();