The Bone handle is used to control all the parameters to a capture
region SOP in an interactive manner.  It creates a "pill" which can be
manipulated to alter the relevant parameters.

Note: For brevity, a * is used in the parameters where either "bot" or
"top" would be present.  bot refers to the bottom half of the capture
pill, and top to the top half.

Parameters:

    cr_*height     - The distance from the center where the end cap starts.
    cr_*rx, cr_*ry - The radius of the end cap in the x & y directions.
    cr_*rz         - The radius of the end cap in the direction of the pill
    cr_colorb, cr_colorg, cr_colorr - The colour to draw the handle in.
    cr_display     - Whether or not to display the capture geometry.
    cr_tx, cr_ty, cr_tz - The center of the pill
    length         - The native length of the bone
    onoff          - Whether the handle is visible, 1 means visible.
    rx, ry, rz     - The orientation of the pill.
    xyz_order      - How to interpret the rx, ry, and rz.

See Also: Pill
