0026444: Boolean operation "bcut" gives invalid result between solid and halfspace...

0026444: Boolean operation "bcut" gives invalid result between solid and halfspace solid.

Patch for version 670 of OCCT (Git branch CR0_670_FixS).

class BOPAlgo_PaveFiller
method void BOPAlgo_PaveFiller::PutPaveOnCurve
    (const Standard_Integer nV,
     const Standard_Real aTolR3D,
     BOPDS_Curve& aNC,
     const BOPCol_MapOfInteger& aMI,
     BOPCol_DataMapOfIntegerReal& aMVTol,
     const Standard_Integer iCheckExtend)

Do not put the pave on the curve in case if there is already one with the same parameter.
Update tolerance of the existing vertex to reach the new one.

Added test case bugs/modalg_6/bug26444.