Standalone program for computing autocorrelation functions

Created by Peter Kosovan 2005 - ....

The program uses the fast correlation algorithm describe in the book 
of D. Frenkel and B. Smit: Understanding molecular simulation, chapter
4.4.2: Order-n algorithm to measure correlations.

Note that this algorithm cannot be used as is to compute any autocorrelation
function. For those, which are not linearly additive, like MSD, corretction
have to be made to avoid systematic errors.