U2024.02.20-0407: Automatic merge of T1.5.1-870-ge0bf062eb and 17 pull requests

- Pull request #570 at 3539862b4: Experimental glTF 2.0 support with PBR lighting
- Pull request #839 at d00beb983: First phase of https://blueprints.launchpad.net/or/+spec/additional-cruise-control-parameters
- Pull request #876 at f92de7665: docs: add source for documents previously on website to source Documentation folder
- Pull request #882 at 9c456aa92: Blueprint/train car operations UI window
- Pull request #885 at 8f9433364: feat: Add notifications to Menu
- Pull request #886 at 6c0785b6c: Scene viewer extension to TrackViewer
- Pull request #892 at 1f5ba4c81: Signal Function OPP_SIG_ID_TRAINPATH
- Pull request #896 at 5866028cf: First implementation of https://blueprints.launchpad.net/or/+spec/specific-sounds-for-ai-trains
- Pull request #897 at 42f1dd9dc: feat: Improved system information collection
- Pull request #903 at 9bead3304: Downloading route content (Github, zip)
- Pull request #907 at 9b0b04faf: Bug fix for https://bugs.launchpad.net/or/+bug/2047300 Dynamic tracks disappear after long tunnel
- Pull request #911 at 6834af038: docs: Add refactoring as a special type of PR
- Pull request #912 at d5957039e: New Triple Valve Features Vol. 2
- Pull request #914 at 476d67b9a: Adjustments to Duplex steam
- Pull request #915 at 6d911d7c5: Correct calculation error with curve friction
- Pull request #917 at fde18cf49: Lighting Configuration Enhancements
- Pull request #918 at f7ba507b7: Manual - News topics updated since 1.5.1