Better lifecycle / build system

[uwx]

LANGUAGES.md has gotten nearly unmanageably big. There's a few major problems with it:

• It's huge
• It might not be accurate
• It's hard to parse
  • Some languages have extra metadata besides the URL (for example, Fish)
• It has some misspellings
• The main issue has to be manually updated whenever the file is updated
• Weird language names make dealing with the file really annoying (for example, languages with parens or square brackets in the name)

To fix some of these, it would be nice to have a CI-based build system that would take the information out of an easily consumable JSON file (that we can generate), update LANGUAGES.md and update the issue automatically.