[test][strategies] add unit test for pythagoras point box strategy
[test][strategies] add entry for unit test for pythagoras point-box
[multi][core] Move functionalities of multi/core into core
[multi][views] Move range_type<> from multi/ directory.

Also tweak the parameters of the dispatched implementation - reverse the order and add default Tag.
[multi][strategies] Move centroid_average from multi/ directory
[multi][geometries] Move models, concepts and register macros from multi/ directory
[multi][io] Move wkt and dsv implementation for Multi Geometries from multi/ directory
Merge branch 'feature/distance' of github.com:mkaravel/geometry into feature/distance
[multi] Include headers of moved parts from geometry/ directory.
[buffer] remove RobustPolicy from side_on_convex_range
because side of a point w.r.t. a segment cannot be done with rescaling,
due to rounding the point can be located on the other side of the segment
This adds 4 more failing testcases, but it has to be done first because
the solution is not reliable
[buffer] merged implementations of side_on_convex_range
[geometry] Replace headers of parts moved from multi/ directory.
[multi][algorithm/detail] Move most of the code of details from multi/ directory.

This commit doesn't move for_each_range.
Details used only by multi/algorithms aren't moved as well.
[buffer] use intersection_side for checking side on convex range
This fixes many of the issues (in multi_polygon_buffer). However, some
new cases now fail because of this and should be fixed later
[multi] Move algorithms details used only by multi/algorithm from multi/ directory.
[algorithms/detail] Refactor for_each_range and move it from multi/directory.
[algorithms/detail] Fix for_each_range backward compatibility.

In the specialization for Box remove_const before creating box_view<> and passing the object of this type into the Actor::apply().
[geometry] Replace includes of headers from algorithms/detail moved from multi/ directory.
[extensions] Replace includes of headers moved from multi/ directory.
[doc] Update docs WRT the latest relocation of the code from multi/ directory