added quick hull algorithm
added tests for quick_hull algorithm
added quick_hull in visualization
now some parameters are passed by reference, not by value
fixed bug in quick hull
added test for quick hull algorithm
changed std::iterator_traits<RanIter>::value_type to point_2 - our algorithm works with this type(Graham and Andrew work only with point_2 too). Some other small changes
Contour contains point visualization
Merge branch 'quick_hull' of git://github.com/Undin/cg
Merge branch 'visualization'