Merge remote-tracking branch 'origin/master' into 1.6

doc/sphinx/book/administration.rst

doc/sphinx/book/box/box_error.rst

doc/sphinx/book/box/box_index.rst

doc/sphinx/book/box/index.rst

doc/sphinx/book/box/limitations.rst

doc/sphinx/book/box/triggers.rst

doc/sphinx/book/replication/index.rst

doc/sphinx/dev_guide/building_from_source.rst

doc/sphinx/dev_guide/index.rst

doc/sphinx/reference/box.rst

doc/sphinx/reference/fiber-ipc.rst

doc/sphinx/reference/index.rst

doc/sphinx/reference/socket.rst

src/coeio.h

src/say.h