Modify CoordinateSystems.angle(...) API in order to let user know when the angle sign give no indication
about whether the coordinate system is right-handed or left-handed, and clarify javadoc.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1557738 13f79535-47bb-0310-9956-ffa450edef68