Added constant voltage example for kalman filter.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1539703 13f79535-47bb-0310-9956-ffa450edef68
Fix checkstyle warning wrt unneeded parenthesis.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1539704 13f79535-47bb-0310-9956-ffa450edef68