CodeReview: Fixed up r62933 as per NikeRabbit's suggestions (http://www.mediawiki.org/wiki/Special:Code/MediaWiki/62933#c6007):
- Use $wgOut->addWikiMsg() instead of $wgOut->addHtml()
- Escape $param using wfEscapeWikiText() to stop HTML injection
- Add description of the 'code-repo-not-found' message to the 'qqq' array.
I also added a description for 'code-rev-id', which I added in r62934. I am aware that this message is ignored at translate-wiki (as per r62935) but I thought it best to provide a description in any case.