Reduces visibility of internal fields/methods

Reduces the visibility of all fields to private and create setters/getters
when necessary. Exceptions are fields with GuiSync as these need to be
public.

Reduces the visibility of internal methods to private/protected/default when possible.

src/main/java/appeng/util/inv/WrapperInvSlot.java

@@ -45,7 +45,7 @@ public class WrapperInvSlot
 		return true;
 	}
 
-	class InternalInterfaceWrapper implements IInventory
+	private class InternalInterfaceWrapper implements IInventory
 	{
 
 		private final IInventory inv;