Mail Kit: Changed how filter changes work.

* BMailFilter::HeaderFetched() now only alters the entry_ref, and returns
  B_MOVE_MAIL_ACTION to move a mail.
* Instead of potentially moving the file around several times, the
  BMailProtocol now takes care of carrying out the filter action just once,
  including trying to make the file name unique.
* This also allows the IMAP add-on to know the final location of the mail,
  and thus downloading a message actually works.
* However, with my test inbox, it currently hangs, and a current Debugger does
  not work on my older system -- I guess I need to update.
* Replaced the duplicated space mechanism within the "HaikuMailFormatFilter"
  that is substantially faster, and handles all whitespace, not just spaces.
  It will also replace tabs with spaces.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012, Haiku, Inc. All Rights Reserved.
+ * Copyright 2011-2013, Haiku, Inc. All Rights Reserved.
  * Distributed under the terms of the MIT License.
  */
 #ifndef _MAIL_FILTER_H
@@ -21,16 +21,14 @@ public:
 	virtual						~BMailFilter();
 
 	// Message hooks if filter is installed to an inbound protocol
-	virtual	void				HeaderFetched(const entry_ref& ref,
-									BFile* file);
-	virtual	void				BodyFetched(const entry_ref& ref, BFile* file);
+	virtual	BMailFilterAction	HeaderFetched(entry_ref& ref, BFile& file);
+	virtual	void				BodyFetched(const entry_ref& ref, BFile& file);
 	virtual void				MailboxSynchronized(status_t status);
 
 	// Message hooks if filter is installed to an outbound protocol
 	virtual	void				MessageReadyToSend(const entry_ref& ref,
-									BFile* file);
-	virtual	void				MessageSent(const entry_ref& ref,
-									BFile* file);
+									BFile& file);
+	virtual	void				MessageSent(const entry_ref& ref, BFile& file);
 
 protected:
 			BMailProtocol&		fMailProtocol;

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

@@ -43,6 +43,13 @@ public:
 };
 
 
+typedef status_t BMailFilterAction;
+
+#define B_NO_MAIL_ACTION		0
+#define B_MOVE_MAIL_ACTION		1
+#define B_DELETE_MAIL_ACTION	2
+
+
 class BMailProtocol : public BLooper {
 public:
 								BMailProtocol(
@@ -68,10 +75,6 @@ public:
 									BDirectory& dir);
 	virtual	status_t			DeleteMessage(const entry_ref& ref);
 
-	virtual	void				FileRenamed(const entry_ref& from,
-									const entry_ref& to);
-	virtual	void				FileDeleted(const node_ref& node);
-
 			// Convenience methods that call the BMailNotifier
 			void				ShowError(const char* error);
 			void				ShowMessage(const char* message);
@@ -88,17 +91,17 @@ protected:
 			void				ReportProgress(uint32 items, uint64 bytes,
 									const char* message = NULL);
 			void				ResetProgress(const char* message = NULL);
+			void				NotifyNewMessagesToFetch(int32 nMessages);
 
 			// Filter notifications
-			void				NotifyNewMessagesToFetch(int32 nMessages);
-			void				NotifyHeaderFetched(const entry_ref& ref,
-									BFile* mail);
+			BMailFilterAction	ProcessHeaderFetched(entry_ref& ref,
+									BFile& mail);
 			void				NotifyBodyFetched(const entry_ref& ref,
-									BFile* mail);
+									BFile& mail);
 			void				NotifyMessageReadyToSend(const entry_ref& ref,
-									BFile* mail);
+									BFile& mail);
 			void				NotifyMessageSent(const entry_ref& ref,
-									BFile* mail);
+									BFile& mail);
 
 			void				LoadFilters(
 									const BMailProtocolSettings& settings);