0024784: Move documentation in CDL files to proper location

Mostly duplicated comments were removed and missing ones were moved
into dedicated class CDL files.
Some more duplicated comments were removed from CDL files.
Correction of merge

src/BRepSweep/BRepSweep.cdl

@@ -38,14 +38,10 @@ uses
 is
 
     class Builder;
-	---Purpose: Implements the Builder required for Sweep.
 
     class Tool;
-	---Purpose: Provides an indexation of the subShapes of a Shape
-	--          from TopoDS.
-	
+
     class Iterator;
-	---Purpose: Iterator on the subShapes of a shape.
 
     deferred class NumLinearRegularSweep;