reuse it for handle_touch
Also, remove the unused member variable m_strategy from it
Conflicts:
include/boost/geometry/algorithms/detail/overlay/enrich_intersection_points.hpp
11709 and 11710;
Ticket 11709 (is_simple segfault): modify the is_simple algorithm to check a linestring
for emptiness; if an empty linestring is discovered, return false; the actual return
value does not really matter as empty linestrings are considered as invalid, which means
that the behavior of is_simple for empty linestrings is undefined; on the other hand,
we do want to avoid segfaults, which is achieved with the patch; the same approach has
been applied to emtpy rings, and as a result to empty polygons;
Ticket 11710 (empty geometry logic): modify the behavior of the is_simple algorithm with
respect to empty multi-geometries; the old behavior was considering empty multi-geometries
as non-simple, whereas the current behavior is the opposite; this change has been made in
order to be consistent with the fact that empty multi-geometries are considered as valid;
test and check for direction of vectors;
Problem: when checking whether a point q creates a spike or not with respect to two (ordered)
points a and b, the first check performed is whether q, a and b are collinear; if so, then it
is determined whether the vectors q-b and b-a have the same direction or not; for points with
floating-point coordinates, due to rounding errors as well as due to the fact that equality to
zero is checked using some tolerance, the three points may be detected as collinear; however,
when the directions of the two vectors are checked, computations are done without taking into
account any tolerance and this can lead to inconsistent results;
Fix: when checking the directions of the vectors q-b and b-a, compute signs of differences using
numerical tolerances, that is using math::equals() instead of plain comparison operators;
If there are NaN coordinates the conditions cannot be reasonably
calculated, therefore if the condition isn't met check if NaN coordinates
were not involved. This is consistent with the general policy WRT invalid
geometries, the algorithm don't fail but may generate invalid result.
Bugs are related to the handling of interior rings intersecting the second
geometry.
touches(A,A) now calls relate(A,A) besides a Ring/Ring case bcause Rings
have no holes so the simpified version may be used.
originally reported by Jeremy Murphy (GitHub PR #326); the problem is that
when debug_print_complement_graph() is called, std::cout needs to be defined
which requires the inclusion of <iostream> even in non-debug mode; with this
commit the call to debug_print_complement_graph() is guarded by the appropriate
macro and the use inclusion of <iostream> is no longer needed in non-debug mode;
