0028828: New functionalities of BRepFilletAPI_MakeChamfer algorithm

0028828: New functionalities of BRepFilletAPI_MakeChamfer algorithm

Two new functionalities have been added in BRepFilletAPI_MakeChamfer:
- constant throat (the section of chamfer is isosceles triangle, its height is constant in all sections - this is the "throat" of the weld);
- constant throat with penetration(the section of chamfer is right-angled triangle, the first of two surfaces (where is the top of the chamfer) is virtually moved inside the solid by offset operation, the apex of the section is on the intersection curve between moved surface and second surface, right angle is at the top of the chamfer, the length of the leg from apex to top is constant - this is the "throat" of the weld).

- New abstract classes BlendFunc_GenChamfer and BlendFunc_GenChamfInv have been added;
- Class BlendFunc_Chamfer is now descended from BlendFunc_GenChamfer, class BlendFunc_ChamfInv is now descended from BlendFunc_GenChamfInv.
- New class BlendFunc_ConstThroat is descended from BlendFunc_GenChamfer, new class BlendFund_ConstThroatInv is descended from BlendFunc_GenChamfInv.
- New class BlendFunc_ConstThroatWithPenetration is descended from BlendFunc_GenChamfer, new class BlendFund_ConstThroatWithPenetrationInv is descended from BlendFunc_GenChamfInv.
- Class ChFi3d_ChBuilder has now mode of chamfer that can be ClassicChamfer, ConstThroatChamfer and ConstThroatWithPenetrationChamfer.
- Two new DRAW Test Harness commands "chamf_throat" ant "chamf_throat_with_penetration" have been added for the second mode of ChBuilder.
- The interface of DRAW Test Harness command "chamf" changed for symmetric case.