Add TypeDummy and Either helper functions to Utility

- TypeDummy - a type without constructor
- fromLeft and fromRight function for Either
Cleanup and minor refactoring
Add askOpts to Interpreter
Extend Interpreter

- move Analyzer and Server.Common to searchengine
- match what was already in the Server impl and extend the Interpreter
  - use ApiDocument instead of Document
  - use the real Query datatype (Holumbus.Query.Language.Grammar)
  - implement search, insert, delete (single doc) -- not well-tested
- add map function to ContextIndex
- extend testcases
  - different approaches to write tests and use the CM monad
  - more tests
- Query JSON instances are NOT implemented/undefined