Merge remote-tracking branch 'origin/1.7' into 1.8

src/box/execute.c

src/box/iproto.cc

src/box/vinyl.c

src/box/vy_point_iterator.c

src/box/vy_read_iterator.c

src/box/vy_run.c

src/box/vy_tx.c

src/lib/small

test/box/tuple.result

test/box/tuple.test.lua

test/engine/truncate.result

test/engine/truncate.test.lua

test/sql/iproto.result

test/sql/iproto.test.lua

test/vinyl/iterator.result

test/vinyl/iterator.test.lua

test/vinyl/mvcc.result

test/vinyl/mvcc.test.lua