title: initialization: parenthesis vs. equals sign
body: <p>What's the difference between</p>
  <pre><code>T a(b);
  </code></pre>
  <p>and</p>
  <pre><code>T a = b;
  </code></pre>
  <p>and</p>
  <pre><code>T a = T(b);
  </code></pre>
  <p>?</p>