Network Kit: Prepare for HTTP range requests

* The DataReceived hook gets a position argument, making it possible for
listeners to handle out-of-order data (from two range requests at
different positions, for example)
* Adjust HaikuDepot (only user of the API in our sources)
* Add a copy constructor to HTTPRequest that copies the relevant
parameters from an existing request. Makes it easy to repeat a request
with a different range. Could be useful for restarting downloads, or
paralellizing them.
* Add SetRangeStart, SetRangeEnd calls to HTTPRequest, no implementation
yet. I'm putting all the API changes in this commit as it needs to be
synced with a matching haikuwebkit release.
* All archs must update to HaikuWebkit 1.3.0. Previous versions are
broken by this.

headers/os/net/HttpRequest.h

@@ -26,6 +26,7 @@ public:
 									const char *protocolName = "HTTP",
 									BUrlProtocolListener* listener = NULL,
 									BUrlContext* context = NULL);
+								BHttpRequest(const BHttpRequest& other);
 	virtual						~BHttpRequest();
 
 			void				SetMethod(const char* const method);
@@ -38,6 +39,8 @@ public:
 			void				SetAutoReferrer(bool enable);
 			void				SetUserName(const BString& name);
 			void				SetPassword(const BString& password);
+			void				SetRangeStart(off_t position);
+			void				SetRangeEnd(off_t position);
 
 			void				SetPostFields(const BHttpForm& fields);
 			void				SetHeaders(const BHttpHeaders& headers);
@@ -115,6 +118,8 @@ private:
 			BHttpForm*			fOptPostFields;
 			BDataIO*			fOptInputData;
 			ssize_t				fOptInputDataSize;
+			off_t				fOptRangeStart;
+			off_t				fOptRangeEnd;
 			bool				fOptSetCookies : 1;
 			bool				fOptFollowLocation : 1;
 			bool				fOptDiscardData : 1;

headers/os/net/UrlProtocolDispatchingListener.h

@@ -44,7 +44,8 @@ public:
 	virtual void				ResponseStarted(BUrlRequest* caller);
 	virtual void				HeadersReceived(BUrlRequest* caller);
 	virtual void				DataReceived(BUrlRequest* caller,
-									const char* data, ssize_t size);
+									const char* data, off_t position,
+									ssize_t size);
 	virtual	void				DownloadProgress(BUrlRequest* caller,
 									ssize_t bytesReceived, ssize_t bytesTotal);
 	virtual void				UploadProgress(BUrlRequest* caller,

headers/os/net/UrlProtocolListener.h

@@ -62,15 +62,17 @@ public:
 	virtual void				HeadersReceived(BUrlRequest* caller);
 	
 	/**
-		DataReceived(data, size)
+		DataReceived(data, position, size)
 		Frequency:	Zero or more
 		Parameters:	data	 Pointer to the data block in memory
+					position Offset of the data in the stream
 					size	 Size of the data block 
 		
 		 Called each time a full block of data is received.
 	*/
 	virtual void				DataReceived(BUrlRequest* caller,
-									const char* data, ssize_t size);
+									const char* data, off_t position,
+									ssize_t size);
 									
 	/**
 		DownloadProgress(bytesReceived, bytesTotal)

headers/os/net/UrlSynchronousRequest.h

@@ -26,7 +26,8 @@ public:
 	virtual void				ResponseStarted(BUrlRequest* caller);
 	virtual void				HeadersReceived(BUrlRequest* caller);
 	virtual void				DataReceived(BUrlRequest* caller,
-									const char* data, ssize_t size);
+									const char* data, off_t position,
+									ssize_t size);
 	virtual	void				DownloadProgress(BUrlRequest* caller,
 									ssize_t bytesReceived, ssize_t bytesTotal);
 	virtual void				UploadProgress(BUrlRequest* caller,