Merge remote-tracking branch 'origin/1.6' into fix-905-upsert-operation

README.md

doc/sphinx/book/administration.rst

doc/sphinx/book/app_d_plugins.rst

doc/sphinx/book/box/box_introspection.rst

doc/sphinx/book/box/net_box.rst

doc/sphinx/book/box/triggers.rst

doc/sphinx/book/user_guide_getting_started.rst

doc/sphinx/dev_guide/building_from_source.rst

doc/sphinx/getting_started.rst

doc/sphinx/reference/expirationd.rst

doc/sphinx/reference/fiber.rst

doc/sphinx/reference/socket.rst

doc/www/content/newsite/index.yml

src/CMakeLists.txt

src/box/CMakeLists.txt

src/box/alter.cc

src/box/alter.h

src/box/box.cc

src/box/box.h

src/box/engine.cc