FitHiChIP major release

This version contains a major upgrade of both methodology and configuration parameters:

1. implements a novel bias regression technique, in addition to original distance decay modeling, to find out the statistical significant interactions.
2. Supports both coverage specific bias normalization, as well as normalization using ICE.
3. Implements a novel peak to peak background specific interaction detection, and applies it specifically for peak to all (default) interaction modeling. The proposed background modeling is found to significantly reduce the number of false positive interactions.
4. Supports overwriting existing FitHiChIP outputs (if user wants to overwrite the existing output files with a new execution)