using the initial numerical guess of whichever vector is already
known to choose our projection planes.
And add a mechanism to defer showing the text window or
regenerating, in order to simplify dependencies on valid actives.
Also yes/no/cancel when about to abandon an unsaved file, and a
bugfix when rotating a rot/trans point.
[git-p4: depot-paths = "//depot/solvespace/": change = 1772]
Jonathan Westhues