[set ops] replace included unit test by unit test
[set ops] added missing include (fstream)
[set ops] add missing includes; remove unnecessary ones
[test] add missing include (fstream)
[set ops] Barend's review: (1) remove unused variables; (2) fix #includes; (3) remove Linestring const*;
Other: remove unused argument in process_turn;
[set ops] remove unused code in #if 0/#endif block; remove some obvious comments;
[set ops] Barend's review: (1) fix #includes; (2) remove //===... comment lines; (3) put struct pointlike_pointlike_point in detail_dispatch namespace;
Other: remove difference_intersection_pointlike_pointlike_point struct (not used)
[set ops] Barend's review: (1) fix #includes; (2) remove //===.. lines; (3) rename AssignPolicy to assign_policy (not a template parameter);
[test][algorithms] add tests for set operations of L/L and P/P geometries; update copyright header;