Navigation: a Blender preset (#1356)

Middle drag orbits, Shift+middle pans, Ctrl+middle zooms; right drag leaves the camera alone. Opt-in preset; the default is unchanged. Fixes #1090.

docs/book/src/guide/ui-tour.md

@@ -25,7 +25,7 @@
   Esc or a click elsewhere closes the list. Clicking again on the same spot, with nothing changed
   in between, selects the next thing in that list. The
   wheel zooms at the cursor, the middle button pans and right-drag orbits freely (the mouse
-  preset in Preferences switches to SolidWorks, Inventor, Alias, Tinkercad, OpenSCAD or Touchpad style). On a
+  preset in Preferences switches to SolidWorks, Inventor, Alias, Blender, Tinkercad, OpenSCAD or Touchpad style). On a
   trackpad, pinch zooms and two-finger scroll pans (Navigation › Two-finger scroll pans;
   off: scroll zooms like the wheel); mouse wheels zoom and the thumb wheel pans sideways.
   Shift+middle orbits freely