[concatenate_iterator] make the iterator bidirectional
[point_iterator] fix constructor calls for concatenate_iterator
[concatenate iterator] re-factor unit test; add tests for bidirectional iterators;
[test][iterators] added copyright header
[test][iterators] re-factor test code for flatten and concatenate iterators
[test][point iterator] re-factor test code; add tests for points_front, points_back, points_reverse_iterator; test point_iterator as bidirectional iterator
[point_iterator] add free functions points_front and points_back that return the first and last point of a geometry
[flatten_iterator] implement decrement operation for flatten iterator
[point_reverse_iterator] implement reverse iterator for geometries
Merge branch 'develop' of https://github.com/boostorg/geometry into feature/point_iterator
[test][iterators] qualify free functions as inline
[equals][relate] Add equals() Ls/MLs, MLs/MLs. Fix relate(L/L).

Also use relate() in equals(Ls,Ls) because collect_vectors() approach doesn't work properly for non-simple or even opposite/reversed Linestrings.

Fix how 'u' is handled in relate() in the edge case when there are more 'u' operations in the same point, also when 'u' is on the first endpoint followed by 'i' on the same IP.

Add tests for equals() and relate().
[equals] Add missing copyright info
[test][iterators] replace #include of type traits by the specific one used (is_const)
[point_iterator_type] replace #include of type traits by the specific one used (is_const)
[doc] Added doc for parameters Doxygen was missing
Merge pull request #21 from mkaravel/feature/point_iterator

Feature/point iterator
[doc] Updated make_qbk
Merge pull request #22 from mkaravel/feature/setops

Feature/setops
[doc] Moved Doxygen html files (conform index) such that they can be deleted more convenient.