Use metasync.cb(fn) to optimize async array utilities
Use metasync.cb(fn) to optimize async array utilities

Refs: https://github.com/metarhia/MetaSync/issues/51
Refs: https://github.com/metarhia/MetaSync/issues/52
PR-URL: https://github.com/metarhia/MetaSync/pull/66

DzyubSpirit/MetaSync,DzyubSpirit/MetaSync,metarhia/MetaSync