package daemon: Add support for activation change request

* daemon: Handle new request B_MESSAGE_COMMIT_TRANSACTION. It activates
  and deactivates given sets of packages. The new packages must be
  placed in a directory in the administrative directory. The daemon
  moves them to the packages directory and the deactivated packages to
  a subdirectory it creates. It also save the old activation state
  there.
* Add private BActivationTransaction, describing an activation change
  transaction.
* BDaemonClient: Add CommitTransaction(), which sends a given
  BActivationTransaction as a B_MESSAGE_COMMIT_TRANSACTION request to
  the daemon.

Completely untested yet.

headers/private/package/DaemonClient.h

@@ -11,6 +11,9 @@
 
 #include <Messenger.h>
 #include <package/PackageDefs.h>
+#include <String.h>
+
+#include <package/DaemonDefs.h>
 
 
 namespace BPackageKit {
@@ -23,7 +26,13 @@ class BPackageInfoSet;
 namespace BPrivate {
 
 
+class BActivationTransaction;
+
+
 class BDaemonClient {
+public:
+			class BCommitTransactionResult;
+
 public:
 								BDaemonClient();
 								~BDaemonClient();
@@ -31,17 +40,57 @@ public:
 			status_t			GetInstallationLocationInfo(
 									BPackageInstallationLocation location,
 									BInstallationLocationInfo& _info);
+			status_t			CommitTransaction(
+									const BActivationTransaction& transaction,
+									BCommitTransactionResult& _result);
 
 private:
 			status_t			_InitMessenger();
 			status_t			_ExtractPackageInfoSet(const BMessage& message,
 									const char* field, BPackageInfoSet& _infos);
 
+			status_t			_CommitTransaction(
+									const BActivationTransaction& transaction,
+									BCommitTransactionResult& _result);
+
 private:
 			BMessenger			fDaemonMessenger;
 };
 
 
+class BDaemonClient::BCommitTransactionResult {
+public:
+								BCommitTransactionResult();
+								BCommitTransactionResult(int32 error,
+									const BString& errorMessage,
+									const BString& errorPackage,
+									const BString& oldStateDirectory);
+								~BCommitTransactionResult();
+
+			void				SetTo(int32 error, const BString& errorMessage,
+									const BString& errorPackage,
+									const BString& oldStateDirectory);
+
+			status_t			Error() const;
+			BDaemonError		DaemonError() const;
+									// may be B_DAEMON_OK, even if Error() is
+									// != B_OK, then Error() is as specific as
+									// is known
+			const BString&		ErrorMessage() const;
+									// may be empty, even on error
+			const BString&		ErrorPackage() const;
+									// may be empty, even on error
+
+			const BString&		OldStateDirectory() const;
+
+private:
+			int32				fError;
+			BString				fErrorMessage;
+			BString				fErrorPackage;
+			BString				fOldStateDirectory;
+};
+
+
 }	// namespace BPrivate
 }	// namespace BPackageKit