Push Matrix1,2,3,4 in public API, and added a rational in the package javadoc.
This is the same than what Vecmath (from Java3D) and Geotk did.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1521666 13f79535-47bb-0310-9956-ffa450edef68