small changes to Trung body files

doc/src/body.txt

doc/src/fix_wall_body_polygon.txt

doc/src/fix_wall_body_polyhedron.txt

doc/src/pair_body_rounded_polygon.txt

doc/src/pair_body_rounded_polyhedron.txt

examples/body/in.cubes

examples/body/in.pour3d

examples/body/in.squares

examples/body/in.wall2d

examples/body/log.9Jul18.body.cubes.g++.1

examples/body/log.9Jul18.body.cubes.g++.4

examples/body/log.9Jul18.body.pour3d.g++.1

examples/body/log.9Jul18.body.squares.g++.1

examples/body/log.9Jul18.body.squares.g++.4

examples/body/log.9Jul18.body.wall2d.g++.1

examples/body/log.9Jul18.body.wall2d.g++.4

src/BODY/body_rounded_polygon.cpp

src/BODY/body_rounded_polyhedron.cpp

src/BODY/fix_wall_body_polygon.cpp

src/BODY/fix_wall_body_polyhedron.cpp