New features

• Improved display of record attributes by displaying each record entry as a single node with nested attribute nodes
• Support reading class files compiled by Java 18
• Added a placeholder panel with instructions in the IDEA tool window

Bug fixes

• Menu items with and without icons were not aligned on macOS
• PermittedSubclassesAttribute and RecordAttribute were saved incorrectly and corrupted the class file
• For Java 9+, the tree of JRE classes always showed the classes of the currently used JRE