/core/commands - distinct between mandatory and non mandatory commands, support for base commands (marked as base in IANA's ftp commands listing)
/core/parsers/base - base parsing functionality wrapper
/core/parsers/features - fixed feature extraction, added support for feature add, support check, feature parameters getter, reuse of /core/parsers/base
/core/parsers/parser - small modifications related to /core/parsers/core functionality reusage
/client/commands - added support for []byte responses externalization on control connection