message: Fix Bottleneck.h already have such a check and CGAL dependency is only due to Bottleneck
diff: #include <cassert>
  #include <cmath>
  -// Make compilation fail - required for external projects - https://github.com/GUDHI/gudhi-devel/issues/10
  -#if CGAL_VERSION_NR < 1041101000
  -# error Alpha_complex_3d is only available for CGAL >= 4.11
  -#endif
  -
  namespace Gudhi {
  namespace cover_complex {
  