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_cxx/data/parser/cxx/CxxAstVisitor.cpp

@@ -40,7 +40,7 @@ CxxAstVisitor::CxxAstVisitor(
 					return declName->toNameHierarchy();
 				}
 			}
-			return NameHierarchy("global");
+			return NameHierarchy("global", NAME_DELIMITER_UNKNOWN);
 		}
 	);
 	m_typeNameCache = std::make_shared<TypeNameCache>([](const clang::Type* type) -> NameHierarchy
@@ -53,7 +53,7 @@ CxxAstVisitor::CxxAstVisitor(
 					return typeName->toNameHierarchy();
 				}
 			}
-			return NameHierarchy("global");
+			return NameHierarchy("global", NAME_DELIMITER_UNKNOWN);
 		}
 	);