Generic importer framework with one dataset made specially for EgoMath.
Possible options for wiki dataset are:
* wiki_to_wikis - e.g., enwiki-20130204-pages-articles.xml -> enwiki-20130204-pages-articles.part*.xml
* wikis_to_huge_math - e.g., enwiki-20130204-pages-articles.part*.xml -> math-enwiki-20130204-pages-articles.xml.part*.xml.pages
* wiki_maths_to_wiki_math - e.g., math-enwiki-20130204-pages-articles.xml.part*.xml.pages -> math-all.pages
* wiki_math_to_pages - e.g., math-all.pages -> output/*/*.html
* test_queries - perform a set of test queries