Wiki formatting is applied to code snippets too

When a text block is indented, it is considered as a code snippet and displayed in monospace font. That's fine, however, wiki formatting rules are still applied to this block. This can be a problem if the block contains say square brackets, as they will be considered as links and the output will be garbled.

Possible solutions:
* Do not apply wiki formatting rules to indented code blocks.
* Provide a formating rule so that specific chars can be escaped. The tilde (~) that is used in phpWiki does not seem to work in this wiki.