1. JoinWLines algorithm has been improved.
2. Reference to the V-boundaries is deleted when computing step.
3. Decreasing the tolerance when computing parameters of WLine.
4. Adding boundary point is forbidden if it lies in prolongation of found ones.
5. Possible reason of exception has been eliminated.
6. Processing of critical point has been improved.
Test cases for this issue have been created.
Correction of some test case(s).
Test case bugs/modalg_6/bug26310_4 is added
Update of test-cases for issue #26310