This pull request contains the FourierTracker observable, which tracks the system drift using the maximum of Fourier expansion of some function over the system restricted only to component with given wavenumbers. Moreover, observable DensityHistogram is added, which calculates snapshot-averaged density histogram over the system, possibly cancelling out system drift using a tracker such as FourierTracker.
This pull request contains the FourierTracker observable, which tracks the system drift using the maximum of Fourier expansion of some function over the system restricted only to component with given wavenumbers. Moreover, observable DensityHistogram is added, which calculates snapshot-averaged density histogram over the system, possibly cancelling out system drift using a tracker such as FourierTracker.