Implement windows 8.1+ notifications

This splits notifications up into multiple backends
currently only libnotify on unix and win8 toasts.

The win8 backend was originally written by @leeter
though heavily modified.

src/fe-gtk/notifications/notification-libnotify.c

@@ -0,0 +1,73 @@
+/* HexChat
+ * Copyright (C) 2015 Patrick Griffis.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#include "config.h"
+#include <glib.h>
+#include <libnotify/notify.h>
+
+static gboolean strip_markup = FALSE;
+
+void
+notification_backend_show (const char *title, const char *text, int timeout)
+{
+	NotifyNotification *notification;
+
+	if (strip_markup)
+		text = g_markup_escape_text (text, -1);
+
+	notification = notify_notification_new (title, text, "hexchat");
+	notify_notification_set_hint (notification, "desktop-entry", g_variant_new_string ("hexchat"));
+
+	notify_notification_set_timeout (notification, timeout);
+	notify_notification_show (notification, NULL);
+
+	g_object_unref (notification);
+	if (strip_markup)
+		g_free ((char*)text);
+}
+
+int
+notification_backend_init (void)
+{
+	GList* server_caps;
+
+	if (!NOTIFY_CHECK_VERSION (0, 7, 0))
+		return 0;
+
+	if (!notify_init (PACKAGE_NAME))
+		return 0;
+
+	server_caps = notify_get_server_caps ();
+	if (g_list_find_custom (server_caps, "body-markup", (GCompareFunc)g_strcmp0))
+		strip_markup = TRUE;
+	g_list_free_full (server_caps, g_free);
+
+	return 1;
+}
+
+void
+notification_backend_deinit (void)
+{
+	notify_uninit ();
+}
+
+int
+notification_backend_supported (void)
+{
+	return notify_is_initted ();
+}