The structure `Fmorpho_line` is used to
handle morpho lines in the continuous plane.
Indeed, if the morpho lines obtained from digital images contain discrete
(integer) coordinates, one may want to process the morpho lines using
continuous operators, such as geometric smoothing. The resulting morpho
lines are no more made by discrete coordinates.
In a `Fmorpho_line`, the points are recorded using the `Point_fcurve` structure (See
Section 6.6).

mw 2004-05-05