-Added field to StepOutsideSegmentBoundariesException to denote if the
excluded step was in the future of the target GPSSegment;
-Corrected GPSSegment's average step length and frequency methods while
returning from an empty step state;
-Created GPSSegment method to return current SL GPSSegment objects;
-Corrected AutoGaitModelerAnalyserTests' wrong expected values and
output methods;
-Corrected bug in SLI where SL's at the tip of the segment weren't
registered;