BDaemonClient: Add support for creating activation transactions

* BActivationTransaction:
  - Remove non-trivial constructor.
  - Remove package list parameters from SetTo().
  - Add AddPackageTo{Dea,A}ctivate().
* BDaemonClient:
  - Add CreateTransaction(). It creates a transaction directory and
    initializes a BActivationTransaction. Packages to de-/activate have
    to be added afterwards.
  - Add BCommitTransactionResult::FullErrorMessage().

headers/private/package/DaemonClient.h

@@ -16,6 +16,9 @@
 #include <package/DaemonDefs.h>
 
 
+class BDirectory;
+
+
 namespace BPackageKit {
 
 
@@ -44,6 +47,11 @@ public:
 									const BActivationTransaction& transaction,
 									BCommitTransactionResult& _result);
 
+			status_t			CreateTransaction(
+									BPackageInstallationLocation location,
+									BActivationTransaction& _transaction,
+									BDirectory& _transactionDirectory);
+
 private:
 			status_t			_InitMessenger();
 			status_t			_ExtractPackageInfoSet(const BMessage& message,
@@ -81,6 +89,8 @@ public:
 			const BString&		ErrorPackage() const;
 									// may be empty, even on error
 
+			BString				FullErrorMessage() const;
+
 			const BString&		OldStateDirectory() const;
 
 private: