Temporary commit.
Merge branch 'master' of github.com:tarantool/tarantool into fiber-file-io

Conflicts:
	src/CMakeLists.txt
fiber-io tests.
Merge branch 'master' of github.com:tarantool/tarantool into fiber-file-io
Cleanup code.
Don't use static variables.
Rename dfio to coeio_file.
'fio' (cooperative file I/O) package: style fixes

Add comments, renames.
Merge remote-tracking branch 'origin/master' into fiber-file-io
Merge branch 'master' of github.com:tarantool/tarantool