Fixed perimeter calculation
Add +1 to Feret Calculation since images are zero based.

A 100x100 pixel image goes from 0,0 to 99,99. Therefor Math.abs(x2-x1) + 1 must be used to get the length of 100 for one side.
add zero check before division
added smallest enclosing rectangle calculation
added eccentricity calculation which relies on the smallest enclosing rectangle
reset output before adding new values
add tests for geometric descriptor sets, result taken from imagej1
Merge pull request #43 from imagej/geometrictests

thanks Daniel