4.  Rename mouse_keybd to direct_manipulation, since it will also
    handle the tablet events.
5.  Implement a tangency control at every control point?
6.  "Stroke curve" creation with the pencil tool - DONE (a hack).
8.  Implement a mirror tool (creates geometry by reflecting it, also
    acts as a cutting plane, like a true mirror).
9.  Fix selection pick radius.
11. When sketching on the tablet with the stylus, remove the cursor
    and replace it with a 3D picture of the stylus drawn in the
    correct tilt orientation with respect to the edit plane.
12. Solid modeler with motion: SOLID -> DEVICE -> SOLID
    SOLID:  degrees of freedom >= 0, for example a lid, or a door.
    DEVICE: degrees of freedom >= 1, for example a hinge.
14. Implement a trail file viewer/editor.
18. Implement Lyche-Morken algorithm "A Data-Reduction Strategy for
    Splines with Applications to the Approximation of Functions and
    Data". This is necessary in order to solve item 6 above.
19. Implement bounding box selection.
20. Implement shift-click point A, shift click point B interpolation
    point set selection.
21. Implement control-click point selection and control-click curve
    selection.
22. Implement curve-move and curve-copy operations.
23. Implement sketch tracing functionality.
24. Add automatic sketch tracing functionality (automatic curve creation 
    via the Lyche-Morken algorithm).
25. Implement a KDE interface for the modeler, use kiconedit or kdevelop
    as an example.
26. Implement a proper regeneration graph.
28. Optimize the BSP tree, try to reuse the code from the display list.
29. Resizing of the window should NOT have the zoom effect on the view,
    because zoom already has a separate control. Resizing the window should
    reveal more of the model at the same detail level as before.
30. It should be possible to modify the curve as follows:
    a. direct manipulation of the interpolation points.
    b. direct manipulation of the tangents.
    c. indirect manipulation of the interpolation points and tangents
       (by dragging a point somewhere between two interpolation points,
       where both bracketing interpolation points can be displaced by a
       fraction of the drag vector, or the neighboring tangent can be
       adjusted).
31. Make facet import procedure transform the facets such that the
    center of their bounding box corresponds to the origin of the
    world coordinate system. Then a transform procedure can be applied
    to move the facets.
32. Implement constraint driven cross section modeling tool -
    arcs, lines, conics.
33. Market a physical training deck of cards (each card has the workout for the
    day on it). Extending this further, it may be possible to generate similar
    cards for daily use for sad and lonely people without lives who can not
    decide how to best spend their time. A good brand name would be 
    "Ugly duckling".
34. The AMPAD does not need to update with the view - sometimes it helps 
    to have a stationary grid for reference.
35. TechPad - an electronic AMPAD for storing technical sketches with
    annotations.
36. GrafittiPad - a 3D texturing tool for illustrating TechPad models.
37. Read "Тихий Дон" and "Поднятая Целина" Шолохова
38. Implement automatic axis of rotation detection for a 2D cross-section
    sketch of a surface of revolution. Essentially - detect the axis of
    symmetry in the sketch.
39. Redefine soft points to reference a curve at such that on each
    successfull regeneration they reference the curve at the location
    closest to the last regenerated position of the soft point. This
    would approximate the behaviour of the arc length parameterized
    reference point. The way to implement this is to call the
    optimizer to find the closest point on the curve to a given point
    (last 3D position of the soft point). The code for this is already
    available, so it's worth trying.
40. Implement proportional update for curves, and reimplement the
    above feature (soft point regen), so that it wouldn't be the hack
    that it is now.
41.