Package Kit: Implement progress notifications.

- BJobStateListener: Add progress state and corresponding hook.
- FetchFileJob: Notify job progress hook on libcurl notifications.
- UserInteractionHandler: Add hooks for download progress and checksum
  validation progress.
- PackageManager: inherit from JobStateListener and watch for job
  notifications for internally generated jobs. Forward to corresponding
  UserInteractionHandler hooks as needed.
- Adapt pkgman, HaikuDepot and package_daemon to above changes.
  Neither HaikuDepot nor package_daemon's progress hooks are wired up to
  do anything yet though.

headers/os/package/Job.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011, Haiku, Inc.
+ * Copyright 2011-2013, Haiku, Inc.
  * Distributed under the terms of the MIT License.
  */
 #ifndef _PACKAGE__JOB_H_
@@ -22,6 +22,7 @@ struct BJobStateListener {
 
 								// these default implementations do nothing
 	virtual	void				JobStarted(BJob* job);
+	virtual	void				JobProgress(BJob* job);
 	virtual	void				JobSucceeded(BJob* job);
 	virtual	void				JobFailed(BJob* job);
 	virtual	void				JobAborted(BJob* job);
@@ -30,7 +31,8 @@ struct BJobStateListener {
 
 enum BJobState {
 	JOB_STATE_WAITING_TO_RUN,
-	JOB_STATE_RUNNING,
+	JOB_STATE_STARTED,
+	JOB_STATE_IN_PROGRESS,
 	JOB_STATE_SUCCEEDED,
 	JOB_STATE_FAILED,
 	JOB_STATE_ABORTED,