moving over to :lists.duplicate

* List.duplicate makes exponentially more :lists.duplicate/3 calls
  than :lists.duplicate/2.
* it also yields better slightly results than String.duplicate.
fixing inspect pretty: false option

* inspect pretty: false calls Wadler.format with :infinity
  as line width.
* Wadler.fits? with w=:infinity always returns true.
* Wadler.format with w=:infinity will only use Flat mode,
  not adding any line breaks.
Mix not using pretty printing

* Added pretty: false option to all inspect calls.