Rewrite: Add more TypeScript

[arildm]

TypeScript is currently partially introduced. Typed code is typically less prone to bugs, and easier to understand and modify. With more typing in place, further modifications will be easier to manage.

Add types to:

• [x] API requests
• [x] Config
• [x] util
• [x] Boilerplate (index, main, app, data_init, korp.module)
• [x] CQP
• [x] CorpusListing
• [x] Url query params
• [x] Auth
• [x] controllers/
  • [x] comparison_controller
  • [x] example_controller
  • [x] kwic_controller
  • [x] statistics_controller
  • [x] trend_diagram_controller
  • [x] word_picture_controller
• [ ] statemachine
• [ ] sidebar
• Everything else