[buffer][fix] Mark points in buffered areas as not startable instead of discarding them

Within can have in rare cases a rounding issue. We don't discard this
point, so it can be used to continue started rings in traversal. But
will never start a new ring from this type of points.

This fixes p17
[algorithms][buffer] fix header for inclusion of disjoint: it is
the point-box and not the box-box version that is needed; also
the call to disjoint is not done via the free function but rather
using the disjoint dispatch struct
[index] Optimize R* choose_next_node - remove sort() and cleanup
[index] Update copyright info
[overlay] Fix Range concepts conformance for interior rings and multi ranges.
[convert] Replace index type to unsigned
[range_by_section] Fix Range concepts conformance for interior rings and multi ranges.
[index] Fix compilation error - invalid variable name in assert.
[append] Fix interior rings and multi Range concept usage.
[convert] Fix Range concept usage.
[assign_box_corners] Fix Range concept usage.
[views] Fix compilation error in box_view caused by the change of a detail::assign_box_corners_oriented() body.

This function requires Range but was using operator[] which isn't a part of Range concept.
And box_view passed a raw pointer into this function.
So now a temporary range std::pair<> is created and passed, this might be changed if point_view stored boost:array<>.
It could be directly passed into the assign_box_corners_oriented.
Merge pull request #127 from mkaravel/fix/buffer-include-header

[algorithms][buffer] fix header for inclusion of disjoint
Merge branch 'feature/buffer' into develop
Merge branch 'develop' of github.com:boostorg/geometry into develop
[index] Remove/modify some comments
[index] Fix unused type warnings in experimental serialization code
[index] Remove unneeded pushable_array container
Merge branch 'develop' of github.com:boostorg/geometry into develop
[index] Add alternative ABL handling - using heap instead of sorted container

Code is commented out, left "for the record" as a result of a quick test.
Add some comments about possible improvements.