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/AppDef/AppDef_MyLineTool.cdl

@@ -15,6 +15,9 @@
 -- commercial license or contractual agreement.
 
 class MyLineTool from AppDef
+    ---Purpose: example of MultiLine tool corresponding to the tools of the packages
+    -- AppParCurves and Approx. For Approx, the tool will not addd points
+    -- if the algorithms want some.
 
 uses MultiLine     from AppDef,
      Pnt           from gp,