In PatternMatch, modified the description of the subpixel algorithm to Orrin...

In PatternMatch, modified the description of the subpixel algorithm to Orrin Thomas's centroid/adaptive method.  Removed references to Eccentricity Ratio and Residual Tolerance. Added the 'fitchip' WindowSize box figure. A few minor additional corrections or modications throughout. Fixes #969.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@4745 41f8697f-d340-4b68-9986-7bafba869bb8