Add schemas 3.1.0-2024-04 and XYZ-3.1.0-2024-04 addressing #15 , #17, #18 and #19.
Please note that this update only affects schemas for the version 3.1.0 IHO dialect (3.1.0-2024-04 and XYZ-3.1.0-2024-04). The 3.0.0 NOAA dialect (3.0.0-2023-08 and XYZ-3.0.0-2023-08) are unchanged. The previous schema versions of the 3.1.0 IHO dialect (3.1.0-2023-08 and XYZ-3.1.0-2023-08) are retained for backwards compatibility.