Fix compile error when using with CGAL

[4c3y]

If ED.h gets included in the same file where CGAL (Computational Geometry Algorithms Library) is used, the compiler will throw an error because of a macro naming conflict.

The compile error happens in the following enum defined in CGAL/enum.h caused by the RIGHT macro defined in ED.h:

enum  Angle
      {
          OBTUSE = -1,
          RIGHT,
          ACUTE
      };

[sturkmen72]

Thank you