Robustness: Zero variance returns constant.
Updated analysis script to use new file format.

The analysis shows the dependence of the prediction accuracy on the length (in time) of the vector of time steps used for the Bayesian analysis.
Added Display#draw_progress_bar function.
Finds automat. optimal length of Bayesian vector.

This is done by brute force: It iterates over all possible values of the vector length and finds the one with the highest accuracy.