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/Standard/Standard_Failure.cdl

@@ -33,13 +33,13 @@ raises
     
 is
 
-    Create returns mutable Failure;
+    Create returns Failure;
     	---Purpose: 
     	--   Creates a status object of type "Failure".
     	---Level: Advanced
 	---C++: alias "Standard_EXPORT Standard_Failure (const Standard_Failure& f);"
 
-    Create (aString: CString) returns mutable Failure;
+    Create (aString: CString) returns Failure;
     	---Purpose: 
     	--   Creates a status object of type "Failure".
         ---Level: Advanced
@@ -87,7 +87,7 @@ is
     	--          at run-time.
         ---Level: Advanced
     
-    NewInstance(myclass; aMessage: CString) returns mutable Failure;
+    NewInstance(myclass; aMessage: CString) returns Failure;
    	---Purpose: Used to construct an instance of the exception object
 	--          as a handle. Shall be used to protect against possible
 	--          construction of exception object in C stack -- that is 
@@ -102,7 +102,7 @@ is
         --          converted to C++ exception.
         ---Level: Advanced, not for regular use
     
-    Caught (myclass) returns mutable Failure raises NoSuchObject;
+    Caught (myclass) returns Failure raises NoSuchObject;
     	---Purpose: Returns the last caught exception. 
 	--          Needed when exceptions are emulated by C longjumps,
         --          in other cases is also provided for compatibility.

src/Standard/Standard_Persistent.cdl

@@ -110,7 +110,7 @@ is
     	    -- assert(p->IsKind(tt));   
     	is static;
 	    
-	This (me) returns mutable Persistent
+	This (me) returns Persistent
 	    ---Purpose:  Returns a handle on the object. 
     	    -- This method is useful only in constructors of persistent 
     	    -- objects when you need a handle on the object being constructed. 

src/Standard/Standard_Transient.cdl

@@ -70,7 +70,7 @@ is
 	    --          Note that multiple inheritance is not supported by OCCT RTTI mechanism.
 	    ---Level: Advanced
 	    
-	This (me) returns mutable Transient
+	This (me) returns Transient
 	    ---Purpose: Returns a Handle which references this object.
 	    ---Warning: Must never be called to objects created in stack.
 	    ---Level: Advanced

src/Standard/Standard_Type.cdl

@@ -70,7 +70,7 @@ is
    ---Purpose:
    --   The constructor for a imported type.
    ---Level: Advanced
-   returns mutable Type;
+   returns Type;
 
    Create(aName           : CString;
 	  aSize		  : Integer;
@@ -79,7 +79,7 @@ is
    ---Purpose:
    --   The constructor for a primitive.
    ---Level: Advanced
-   returns mutable Type;
+   returns Type;
 
    Create(aName           : CString;
 	  aSize		  : Integer;
@@ -90,7 +90,7 @@ is
    ---Purpose:
    --   The constructor for an enumeration.
    ---Level: Advanced
-   returns mutable Type;
+   returns Type;
 
    Create(aName           : CString;
 	  aSize		  : Integer;
@@ -100,7 +100,7 @@ is
    ---Purpose:
    --   The constructor for a class.
    ---Level: Advanced
-   returns mutable Type;
+   returns Type;
 
    ---------------------------------------------------------------------
    ---Category: Comparison between types