rk.power: nicer output, fixing sample information

git-svn-id: https://svn.code.sf.net/p/rkward/code@4876 7936002b-cd1d-0410-9ce3-d7ebf93b5162
layout changes done by roxygen

git-svn-id: https://svn.code.sf.net/p/rkward/code@4877 7936002b-cd1d-0410-9ce3-d7ebf93b5162