title: reduce the capacity of an stl vector
body: <p>Is there a way to reduce the capacity of a vector ?</p>
  
  <p>My code inserts values into a vector (not knowing their number beforehand), and
  when this finishes, the vectors are used only for read operations.</p>
  
  <p>I guess I could create a new vector, do a .reseve() with the size and copy
  the items, but I don't really like the extra copy operation.</p>
  
  <p>PS: I don't care for a portable solution, as long as it works for gcc.</p>