This package provides an API used in CorrelationTrackers.jl and
MaterialReconstruction.jl. There are two kinds of functions and types.
The first kind is used to make small modifications to annealed arrays and be
able to roll back a bad modification. This API consists of two functions:
update_corrfns! and rollback!. The first function must behave like
setindex! but return a rollback token of type AbstractRollbackToken which
can be used by the second function to bring an array to the previous state.
The second kind contains types like AbstractTracker, S2Tracker, L2Tracker
and so on which are used to designate a correlation function plus phase which
must be used in the annealing process. There are also tracked_data,
tracked_length and tracked_directions functions which you may wish to
implement in correlation tracker.