Implement getting a BInstallationLocationInfo

* Rename PackageDaemonDefs.h to DaemonDefs.h.
* Replace the MESSAGE_GET_PACKAGES by the new
  B_MESSAGE_GET_INSTALLATION_LOCATION_INFO, which not only returns the
  packages, but also other information about the installation location.
* daemon: Volume: Implement a change count which is bumped whenever
  packages are activated/deactivated/added/removed. Cache the reply
  for a location info request, using the change count to check whether
  it is still up-to-date.
* Add private BDaemonClient for communication with the daemon.
* BRoster:
  - Add GetInstallationLocationInfo() using BDaemonClient.
  - Reimplement GetActivePackages(), using
    GetInstallationLocationInfo().

headers/private/package/DaemonClient.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2013, Haiku, Inc. All Rights Reserved.
+ * Distributed under the terms of the MIT License.
+ *
+ * Authors:
+ *		Ingo Weinhold <[email protected]>
+ */
+#ifndef _PACKAGE__PRIVATE__DAEMON_CLIENT_H_
+#define _PACKAGE__PRIVATE__DAEMON_CLIENT_H_
+
+
+#include <Messenger.h>
+#include <package/PackageDefs.h>
+
+
+namespace BPackageKit {
+
+
+class BInstallationLocationInfo;
+class BPackageInfoSet;
+
+
+namespace BPrivate {
+
+
+class BDaemonClient {
+public:
+								BDaemonClient();
+								~BDaemonClient();
+
+			status_t			GetInstallationLocationInfo(
+									BPackageInstallationLocation location,
+									BInstallationLocationInfo& _info);
+
+private:
+			status_t			_InitMessenger();
+			status_t			_ExtractPackageInfoSet(const BMessage& message,
+									const char* field, BPackageInfoSet& _infos);
+
+private:
+			BMessenger			fDaemonMessenger;
+};
+
+
+}	// namespace BPrivate
+}	// namespace BPackageKit
+
+
+#endif	// _PACKAGE__PRIVATE__DAEMON_CLIENT_H_