- Proper implementation of compare_x(Line_2,Line_2,Line_2), to have
correct degree (was using compare_x(l,h1,l,h2) before, now special
implementation in predicates/kernel_ftC2.h).
- Cleaned up Segment_2.C to use *are_ordered_along_line predicates
- Prefix CGAL:: for sqrt in Circle_2.C
- Removed useless protect macros.
- equal_lineC2() rewrite.
- using sign_of_determinant() where appropriate.
- Put a few functions between //CGAL_NO_FILTER_BEGIN and //CGAL_NO_FILTER_END.
- Removed buggy CGAL_kernel_exactness_precondition().