style fix
Field in cpu/shinyak is divided into Field and BasicField.
BasicField has only essential methods for everyone.

TrackedRensaResult is removed since no one is using.

TrackResult is renamed to RensaTrackResult

Removed unnecessary include and constants.

Adds comment

RensaTrackingStrategy is renamed to RensaTracker.
BasicField::simulateWithTracker returns BasicRensaResult.
BasicField::simulate returns BasicRensaResult.
Removes FieldBitField::operator().
RensaTracker uses pointer instead of reference.