title: Drop all of a kind of thing
body: <p>I would like the player to be able to drop all of a <em>kind of thing.</em>  e.g.</p>
  
  <pre><code>piece is  a kind of thing.
  Pawn is a kind of piece.
  Rook is a kind of piece.
  
  The player carries 8 pawns.
  The player carries 2 rooks.
  </code></pre>
  
  <p>Now if:</p>
  
  <pre><code>&gt;drop all rooks
   Rook: Dropped.
   Rook: Dropped.
  </code></pre>
  
  <p>But if:</p>
  
  <pre><code>&gt;drop all pieces
   You can't use multiple objects with that verb.
  </code></pre>
  
  <p>How can I uses pieces to mean all rooks and pawns?</p>