IsPlaybackFile return nil if file is a playback file and is a supported version.

NewPlayback is the preferred method of implementation for the Playback type.

NewRecorder is the preferred method of implementation for the FileRecorder type.

sentinal errors for IsPlaybackFile().

sentinal error returned by GetPlayback() if a hash error is encountered.

Playback is used to reperform the user input recorded in a previously recorded file.

Recorder transcribes user input to a file.