title: Rowmax as new column in data table
body: <p>I have rank scores of countries for different variables.</p>
  
  <p>I would like to create a column with the maximum rank that occurs per row.</p>
  
  <p>Say the data look something like:</p>
  
  <pre><code>    A B C D E F G H I .... 
  V1  1 4 5 3 12 . 6 9 83
  V2  . . 4 6 1 4  7 6 32
  </code></pre>
  
  <p>So A - X are countries. In rows V1 up you have various variables and in the cells you have the rank score relating to the variable.</p>
  
  <p>Problem is that some countries for whatever reasons don´t score in relation to certain variables, perhaps because V1 is not relevant to country C or whatever.</p>
  
  <p>So in the end I´d like something like</p>
  
  <pre><code>A B C D E F G H I ....   newv
  V1  1 4 5 3 12 . 6 9 83  83
  V2  . . 4 6 1 4  7 6 5    6
  </code></pre>