IMAP: downloading mails is now working.

* Changed the way the attributes are written to make sure that everything
  that can be written once is in fact written just once.
* The rename code in BMailProtocol::_ProcessFetchedHeader() was broken,
  and caused the hang of the last commit.

headers/os/add-ons/mail_daemon/MailFilter.h

@@ -21,8 +21,10 @@ public:
 	virtual						~BMailFilter();
 
 	// Message hooks if filter is installed to an inbound protocol
-	virtual	BMailFilterAction	HeaderFetched(entry_ref& ref, BFile& file);
-	virtual	void				BodyFetched(const entry_ref& ref, BFile& file);
+	virtual	BMailFilterAction	HeaderFetched(entry_ref& ref, BFile& file,
+									BMessage& attributes);
+	virtual	void				BodyFetched(const entry_ref& ref, BFile& file,
+									BMessage& attributes);
 	virtual void				MailboxSynchronized(status_t status);
 
 	// Message hooks if filter is installed to an outbound protocol

headers/os/add-ons/mail_daemon/MailProtocol.h

@@ -95,9 +95,11 @@ protected:
 
 			// Filter notifications
 			BMailFilterAction	ProcessHeaderFetched(entry_ref& ref,
-									BFile& mail);
+									BFile& mail, BMessage& attributes);
 			void				NotifyBodyFetched(const entry_ref& ref,
-									BFile& mail);
+									BFile& mail, BMessage& attributes);
+			BMailFilterAction	ProcessMessageFetched(entry_ref& ref,
+									BFile& mail, BMessage& attributes);
 			void				NotifyMessageReadyToSend(const entry_ref& ref,
 									BFile& mail);
 			void				NotifyMessageSent(const entry_ref& ref,
@@ -108,6 +110,10 @@ protected:
 
 private:
 			BMailFilter*		_LoadFilter(const BMailAddOnSettings& settings);
+			BMailFilterAction	_ProcessHeaderFetched(entry_ref& ref,
+									BFile& mail, BMessage& attributes);
+			void				_NotifyBodyFetched(const entry_ref& ref,
+									BFile& mail, BMessage& attributes);
 
 protected:
 			const BMailAccountSettings fAccountSettings;

headers/os/app/Message.h

@@ -489,7 +489,8 @@ public:
 			status_t			SetRect(const char* name, const BRect& value);
 			status_t			SetSize(const char* name, const BSize& value);
 			status_t			SetData(const char* name, type_code type,
-									const void* data, ssize_t numBytes);
+									const void* data, ssize_t numBytes,
+									bool fixedSize = true, int count = 1);
 
 	class Private;
 	struct message_header;