[strategies][agnostic] fix bug in Graham-Andrew strategy:
last is used again after two calls to pop_back() which can invalidate
the reference;
patch: make last a true point rather than a reference
bug reported/patch suggested by David Zhao
[strategies][distance] update doxygen documentation for pythagoras
point-box and box-box strategies
[doc][stratiegies][distance] add pythagoras point-box and box-box strategies
[test] add bigobj flag for union/buffer
[iterators][point_iterator] remove free functions points_front and points_back
[test][iterators] remove tests for points_front and points_back
Merge pull request #79 from mkaravel/feature/remove_points_front_back

Feature/remove points front back
Merge pull request #72 from mkaravel/fix/graham_andrew

[strategies][agnostic] fix bug in Graham-Andrew strategy:
Merge pull request #77 from mkaravel/feature/doc-strategies

Feature/doc strategies
Merge pull request #75 from mkaravel/feature/is_simple

Feature/is simple