Add Enum class, instances and [x..] [x..y] sugar

[chrisdone-artificial]

Easy peasy:

main = do
  IO.print $ List.take 5 $ Enum.enumFrom 1
  IO.print $ Enum.enumFromTo 1 10
  IO.print $ List.take 5 $ Enum.enumFrom 'a'
  IO.print $ List.take 5 $ Enum.enumFrom Bool.False
  IO.print $ List.take 5 $ Enum.enumFrom (Int.toInteger 1)
  IO.print $ List.take 5 $ Enum.enumFrom $
     Maybe.maybe (Error.error "Bad day.") Function.id $ Day.fromGregorianValid (Int.toInteger 2020) 01 01

  -- simple list generators
  IO.print [1 .. 3]
  IO.print $ List.take 5 ['a' ..]

=>

> :main examples/45-enum.hell"
[1,2,3,4,5]
[1,2,3,4,5,6,7,8,9,10]
"abcde"
[False,True]
[1,2,3,4,5]
[2020-01-01,2020-01-02,2020-01-03,2020-01-04,2020-01-05]
[1,2,3]
"abcde"