PK_ERROR_code_t    PK_SURF_find_curves_common
(
--- received arguments ---
PK_SURF_t          surf_1,      --- first surface
PK_SURF_t          surf_2,      --- second surface

--- returned arguments ---
int         *const n_curves,    --- number of common curves
PK_CURVE_t **const curves       --- common curves
)


This function finds curves which are common to two surfaces.


Specific Errors:
    PK_ERROR_geom_topol_mismatch   surface not attached to face
    PK_ERROR_general_body          general body
    PK_ERROR_not_in_same_body      surfs don't belong to same body


The surfaces must be attached to faces of the same body.  All faces
associated with surf_1 are compared with all faces associated with surf_2
to find common edges and hence common curves.

The returned curves may contain duplicates.

If the same surface is given as surf_1 and surf_2 then all curves lying
on edges of faces associated with that surface are returned.