sophia-index: disk index based on sophia database.
Merge branch 'master' into sophia-index

Conflicts:
	src/errcode.h
sophia-index: add sophia space engine.
sophia-index: proper iterator handling and destroy, added basic test.
Merge branch 'master' into sophia-index

Conflicts:
	src/box/CMakeLists.txt
	src/box/index.cc
	src/box/key_def.h
	src/box/space.cc
	src/box/space.h
sophia-index: add sophia engine, proper support replace mode multi-replace,
clean up txn new_tuple on txn_finish.
sophia-index: Explicitly inform a engine about recovery stage change.
Merge branch 'master' into sophia-index
sophia-index: add sophia repository directory.
sophia-index: code style fixes.
sophia-index: make DropIndex engine specific.
Merge branch 'sophia-index'

Conflicts:
	src/box/CMakeLists.txt
	src/errcode.h