workplane: a free constraint works in three-space (e.g. true
distance), and a constraint in a workplane works in that plane
(e.g. projected distance). And make the solver go automatically,
though solver itself has lots of pieces missing.
[git-p4: depot-paths = "//depot/solvespace/": change = 1691]
and point-in-plane. These work, but the equation is still stupid,
solving everything at once and not substituting trivial equations.
[git-p4: depot-paths = "//depot/solvespace/": change = 1677]
take the partial derivatives, and run the Newton's method. This
seems to sort of work with a single distance constraint.
[git-p4: depot-paths = "//depot/solvespace/": change = 1675]
Jonathan Westhues