logic: add name delimiter to NameHierarchy

* NameHierarchy now looks like this: <delimiter>\tm<all the rest>
* made new baseclasses for SettingsMigration and SettingsMigrator
* Use the migration system for SqliteBookmarkStorage as well

src/lib/utility/messaging/type/MessageActivateNodes.h

@@ -10,6 +10,10 @@ class MessageActivateNodes
 public:
 	struct ActiveNode
 	{
+		ActiveNode()
+			: nodeId(0)
+			, nameHierarchy(NAME_DELIMITER_UNKNOWN)
+		{ }
 		Id nodeId;
 		NameHierarchy nameHierarchy;
 	};

src/lib/utility/messaging/type/MessageSearch.h

@@ -36,7 +36,7 @@ public:
 			{
 				if (!m_matches[i].subtext.empty())
 				{
-					ss << m_matches[i].subtext << NameHierarchy::getDelimiter();
+					ss << m_matches[i].subtext << m_matches[i].delimiter;
 				}
 				ss << m_matches[i].name;
 			}