Merge branch 'tuple-ref-refactoring'

src/box/lua/call.cc

src/box/lua/call.h

src/box/lua/index.cc

src/box/lua/index.h

src/box/lua/schema.lua

src/box/lua/tuple.cc

src/box/lua/tuple.lua

src/box/tuple.h

src/ffisyms.cc

test/big/hash.result

test/big/hash_multipart.result

test/big/lua.result

test/box/access_bin.result

test/box/errinj.result

test/box/errinj.test.lua

test/box/select.result

test/box/stat.result

test/box/tuple.result

test/sophia/transaction.result

test/sophia/transaction.test.lua