U2024.03.13-0939: Automatic merge of T1.5.1-913-g91804456c and 16 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 1a5693de5: Blueprint/train car operations UI window
- 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 #903 at f588e3104: Downloading route content (Github, zip)
- Pull request #910 at 97d4569b9: Allow building code using .NET 6 (Windows)
- Pull request #911 at 6834af038: docs: Add refactoring as a special type of PR
- Pull request #912 at f7b85e4bf: New Triple Valve Features Vol. 2
- Pull request #919 at e6c08a220: Added mouse wheel support for controls which can be moved by pressing t…
- Pull request #920 at a94e40312: Update RailDriver in Manual
- Pull request #923 at e0f3c55d8: Add curve squeal to route
- Pull request #924 at 6c2c3cdbe: Default Asset Improvements
- Pull request #925 at e3b1688f7: Fix brakeshoe force bug