sophia-snapshot: gh-556, gh-661

src/box/box.cc

src/box/box.h

src/box/engine.h

src/box/engine_memtx.cc

src/box/engine_memtx.h

src/box/engine_sophia.cc

src/box/engine_sophia.h

src/box/recovery.cc

src/box/recovery.h

src/box/sophia_index.cc

src/sophia/snapshot

third_party/sophia