title: Armadillo vector-matrix multiplication
body: <p>Is it possible to multiply (dot product) a matrix by a vector in Armadillo ?
  It seems to me a basic operation we expect from this kind of library, so it should exist. All my attempts failed up to now:</p>
  
  <pre><code>"matrix multiplication: incompatible matrix dimensions: 1206x36 and 1x1206"
  "matrix multiplication: incompatible matrix dimensions: 1206x36 and 1206x1"
  "matrix multiplication: incompatible matrix dimensions: 1x1206 and 1206x36"
  "matrix multiplication: incompatible matrix dimensions: 1206x1 and 1206x36"
  </code></pre>