[disjoint] move basic disjoint dispatch in algorithms/dispatch/disjoint.hpp; use tag_cast to simplify dispatching
[disjoint/equals] move equals::point_point from algorithms/detail/disjoint/point_point.hpp
to algorithms/detail/equals/point_point.hpp
[disjoint] add error message in algorithms/detail/disjoint.hpp to check
whether this file is included somewhere or not; this file will go away
[disjoint] move disjoint_interrupt_policy from algorithms/detail/disjoint.hpp
to a separate file under policies
[disjoint] add dispatch specialization for point-point and point-box;
move equals::point_point code to proper place;
[disjoint] add dispatch and fix copyright headers
[disjoint] add files in algorithms/detail/disjoint with existing code
and new code (for new geometry combinations); clean-up/simplify
dispatch using tag_cast and clean-up dispatch specializations;
[disjoint] move code from multi/algorithms/disjoint.hpp to files
in algorithms/disjoint/detail; move code from algorithms/distance.hpp
also to algorithms/disjoint/detail and in algorithms/dispatch/disjoint.hpp
[extensions][ttmath] add unary operator-() for ttmath_big (needed for
boost::geometry::math::abs) and also add binary operator-() (needed
because of the unary overlaod)
[buffer] remove inclusion of algorithms/detail/disjoint.hpp
[has self intersections] include header with disjoint interrupt policy
[point on border] replace inclusion of algorithms/detail/disjoint.hpp by algorithms/detail/equals/point_point.hpp
[set ops P/P] replace inclusion of algorithms/detail/disjoint.hpp by algorithms/detail/equals/point_point.hpp
[overlay] replace inclusion of algorithms/detail/disjoint.hpp by algorithms/detail/equals/point_point.hpp
[overlay] replace include of algorithms/detail/disjoint.hpp by algorithms/detail/disjoint/box_box.hpp
[within] replace inclusion of algorithms/detail/disjoint/point_point.hpp by algorithms/detail/equals/point_point.hpp
[relate] replace inclusion of algorithms/detail/disjoint/point_point.hpp by algorithms/detail/equals/point_point.hpp
[strategies] replace inclusion of algorithms/detail/disjoint/point_point.hpp by algorithms/detail/equals/point_point.hpp
[disjoint] add missing includes
[test][disjoint] add unit test for checking which geometry combinations
work with disjoint