Improve rendered HTML formatting for {@code}

Multi-line blocks of example code within:

<pre>{@code
line1...
line2...
line3...
}</pre>

are indented differently than when put in just <pre></pre>. In particular, the first line is not indented.

For an example of the problem, see example.txt for the JavaDoc and rendered .html, and screenshot.png for how this looks in the browser.

I believe this could be fixed if the line break following <pre>{@code were carried over to the .html. For example:

 <pre><code>DateFormat preCode = DateFormat.getDateInstance();

would become:

 <pre><code>
DateFormat preCode = DateFormat.getDateInstance();