IMAP: New folders will now adopt default mail attributes.

* Added a function CopyMailFolderAttributes() that copies the attribute
  layout from the text/x-email default query folder.
* This using the new CopyAttributes() method in libshared that is pretty
  much a copy of a similar method from copyattr. However, I did not
  replace the latter, as that one allows for more fine grained error
  reporting (and attribute filtering).
* Closes ticket #3498.

headers/private/shared/AttributeUtilities.h

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2016 Haiku Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef ATTRIBUTE_UTILITIES_H
+#define ATTRIBUTE_UTILITIES_H
+
+
+#include <SupportDefs.h>
+
+
+class BNode;
+
+
+namespace BPrivate {
+
+
+status_t CopyAttributes(BNode& source, BNode& destination);
+
+
+}	// namespace BPrivate
+
+
+#endif // ATTRIBUTE_UTILITIES_H