0023706: Cannot project point on curve

1.   Approximation of derivative (by Taylor-series and by three points).
2.   Some methods (Degree(), GetType(), D0(), D3(), DN()) are added.
3.   Getting of subInterval's boundaries.
4.   Algorithm for checking if 1st derivative is equal to zero is amended.
5.   Cases are controlled when extrema or Project point do not exist.
6.   GetNormal() function for gp_Vec2d was added.
7.   Computing of Value, D0, D1, D2 and D3 for offset curves was changed.
8.   Limitation of tolerance for derivative computing was added.
9.   Methods for computing trihedron in singularity point are added.
10. Test tests/bugs/moddata_3/bug23706 is added.
11. Restriction on the LastParameter for visualization of 3-D curves. Calling PlotCurve(...) function for last interval.
12. LProp package is modified for tangent computing in singularity point (LProp_CLProps, LProp_SLProps).
13. Added test cases for issue.
Deleting bad test cases for this fix

src/gp/gp_Vec.cdl

@@ -151,7 +151,7 @@ is
      raises VectorWithNullMagnitude
       
      is static;
-
+     
   IsParallel (me; Other : Vec; AngularTolerance : Real)   returns Boolean
         --- Purpose :
         --  Returns True if Angle(<me>, Other) <= AngularTolerance or
@@ -164,7 +164,7 @@ is
      raises VectorWithNullMagnitude
      
      is static;
-
+     
   Angle (me; Other : Vec)  returns Real
         --- Purpose :
         --  Computes the angular value between <me> and <Other>

src/gp/gp_Vec2d.cdl

@@ -136,7 +136,7 @@ is
      raises VectorWithNullMagnitude
       
      is static;
-
+     
   IsParallel (me; Other : Vec2d; AngularTolerance : Real)
      returns Boolean
         ---C++: inline
@@ -212,6 +212,11 @@ is
         --- Purpose : Computes the scalar product
         ---C++: alias operator *
 
+  GetNormal(me)  returns Vec2d is static;
+        ---C++: inline 
+        -- Purpose : Returns a vector {Y(), -X()} which
+        --      is normal to given.
+
   Multiply (me : in out; Scalar : Real)           is static;
         ---C++: inline
         ---C++: alias operator *=

src/gp/gp_Vec2d.lxx

@@ -244,3 +244,8 @@ inline gp_Vec2d operator* (const Standard_Real Scalar,
 			   const gp_Vec2d& V)
 { return V.Multiplied(Scalar); }
 
+inline gp_Vec2d gp_Vec2d::GetNormal() const
+  {
+  return gp_Vec2d(this->Y(), (-1)*this->X());
+  }
+