Minor tunings:
* Renamed Matrices.create(int,int) as createDiagonal.
* Removed dependency to java.awt.geom.AffineTransform in Matrices (the method will still work using the more generic checks).
* Added a test case.
* Trivial javadoc.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1524084 13f79535-47bb-0310-9956-ffa450edef68