1. Introruced new prototype function :  "Elongated ROI median axis segmentation" that provides slices along the median axis.

2. Implemented FVX file save verification.

3. Nifti: implemented code to support the negative values in INT8, INT16, INT32 (old version was truncated). If negative value is present we represent volume as REAL.

4. Nifti: implemented code to support  SLOPE\Intercept (old version was ignored). If non-trivial slope\intercept are present, then we represent volume as REAL.