0024830: Remove redundant keyword 'mutable' in CDL declarations

Redundant keyword 'mutable' removed in CDL files.
In IGESConvGeom_GeomBuilder, unused methods MakeXY() and MakeXYZ() removed.
Method StepAP214_AutoDesignGroupAssignment::Init() replicating same method of the base class is removed as it causes CDL extraction error after above (seemingly irrelevant) changes.

src/GccInt/GccInt_BCirc.cdl

@@ -26,7 +26,7 @@ uses Circ2d from gp,
 
 is
 
-Create(Circ : Circ2d) returns mutable BCirc;
+Create(Circ : Circ2d) returns BCirc;
     	---Purpose: Constructs a bisecting curve whose geometry is the 2D circle Circ.
     
 Circle(me) returns Circ2d from gp

src/GccInt/GccInt_BElips.cdl

@@ -26,7 +26,7 @@ uses Elips2d from gp,
 
 is
 
-Create(Ellipse : Elips2d) returns mutable BElips;
+Create(Ellipse : Elips2d) returns BElips;
     	---Purpose:
     	-- Constructs a bisecting curve whose geometry is the 2D ellipse Ellipse.
     

src/GccInt/GccInt_BHyper.cdl

@@ -26,7 +26,7 @@ uses Hypr2d from gp,
 
 is
 
-Create(Hyper : Hypr2d from gp) returns mutable BHyper;
+Create(Hyper : Hypr2d from gp) returns BHyper;
     	---Purpose:
     	-- Constructs a bisecting curve whose geometry is the 2D hyperbola Hyper.
         

src/GccInt/GccInt_BLine.cdl

@@ -26,7 +26,7 @@ uses Lin2d  from gp,
 
 is
 
-Create(Line : Lin2d) returns mutable BLine;
+Create(Line : Lin2d) returns BLine;
     	---Purpose: Constructs a bisecting line whose geometry is the 2D line Line.
     
 Line(me) returns Lin2d from gp

src/GccInt/GccInt_BParab.cdl

@@ -26,7 +26,7 @@ uses Parab2d from gp,
 
 is
 
-Create(Parab : Parab2d) returns mutable BParab;
+Create(Parab : Parab2d) returns BParab;
     	---Purpose: Constructs a bisecting curve whose geometry is the 2D parabola Parab.
     
 Parabola(me) returns Parab2d from gp

src/GccInt/GccInt_BPoint.cdl

@@ -25,7 +25,7 @@ uses Pnt2d from gp,
 
 is
 
-Create(Point : Pnt2d) returns mutable BPoint;
+Create(Point : Pnt2d) returns BPoint;
     ---Purpose: Constructs a bisecting object whose geometry is the 2D point Point.
     
 Point(me) returns Pnt2d from gp