* OFFSET uses a single preselected object (#1610)
With exactly one offsettable object selected before OFFSET, take it and go
to the side prompt instead of asking to select an object again; a multiple
selection keeps the select-object loop. AutoCAD ignores preselection here,
but this is the requested behaviour for users coming from other tools.
* docs: document the functions touched by #1610
* web: report the open drawing in the viewport title
* docs: document the functions touched by #1717
* web: write the browser document title directly
eframe's web runner ignores egui::ViewportCommand::Title, so the tab and
an embedding page kept showing CADCraft when a drawing was opened,
renamed or became dirty. Write the title through web_sys instead, and
route the change decision through a writer function so the changed-title
path is covered by a native test.
Nicholas Gower