* Option --no-type-checking now disables type checks in SmtEngine

* Option --no-type-checking now disables type checks in SmtEngine
* Adding options --lazy-type-checking and --eager-type-checking
  to control type checking in NodeBuilder, which can now be enabled
  in production mode and disabled in debug mode
* Option --no-checking implies --no-type-checking
* Adding constructor SmtEngine(ExprManager* em) that uses default options