Code syntax testing

- simple code tag (e.g. <php> echo "Hello World"; </php>) <php> echo "Hello World"; </php>

- advanced code tag (e.g. <code php&gt echo "Hello World"; </code&gt)

 echo "Hello World";

- advanced code tag with line numbers (<code php n&gt echo "Hello World"; </code&gt)

 echo "Hello World";

- default code tag (e.g. <code&gt echo "Hello World"; </code&gt)

 echo "Hello World";

- display a list of supported languages (e.g. <code list&gt</code&gt)