Added .wikicount

Completes [this GCI 2013 task](https://www.google-melange.com/gci/task/view/google/gci2013/5859183782002688)
Returns the number of Wikipedia (official or incubator) articles for that language
`.wikicount <lg>` where lg can be a wikipedia code, an ISO 639-3 code, or part of a language name.
`.wikicount update` updates the article counts.