GitHub's flavor of markdown adds fenced code blocks, delimited by triple-backquotes, like this:

    ```
    code
    more code
    ```

That syntax proves quite a bit more convenient in many cases, because it doesn't require modifying every line of the code block to add indentation.  Please consider adding optional support for this in ikiwiki.  Please also consider turning it on by default for new wikis, though not for existing wikis since it could *potentially* break backward compatibility with existing content.