Suggestions to split from core into extensions

Should be split

 * Extension:AskSQL

Special pages

 * Uncategorized categories, files, pages, and templates
 * Unused categories, files, and templates, and orphaned pages
 * Wanted categories, files, pages, and templates
 * Most linked to categories, categories, files, pages, and templates

Maybe

 * Math rendering/texvc
 * It's a bit silly to have in core distribution, most people don't need it and it has lots of external dependencies.