upgrade parent pom

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/compress/trunk@1635920 13f79535-47bb-0310-9956-ffa450edef68
document change in package structure

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/compress/trunk@1635926 13f79535-47bb-0310-9956-ffa450edef68
add some javadocs, check argument to readBits

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/compress/trunk@1635927 13f79535-47bb-0310-9956-ffa450edef68