Fixes #58

• Rewrite tests for the literal (all cases)
• Rewrite tests for the utils
• Rewrite fixtures and put them in a conftest.py
• Rewrite tests for the list class
  • properties head, tail, init, last
  • method prepend
  • method reversed
    Cases: duplicate items
  • method sorted
    Cases: duplicate items, all same items, key provided, reversed
  • method shuffled
    Cases: duplicate items, all same items
  • method map
    Cases: function (T) -> T, function (T) -> U
  • method rotate
    Cases: n = 1, n >= 2, n = 0, n < 0
  • method filter
    Cases: all same items, all "truthy" items, all "falsy" items
  • method mask
    Cases: mask all True, mask all False, mask different length
  • method deduplicate
    Cases: no duplicate items, all same items
  • method reduce
    Cases: ...
  • method reduce_right
    Cases: ...
  • method fold
    Cases: ...
  • method fold_right
    Cases: ...
  • method scan
    Cases: ...
  • method scan_right
    Cases: ...
  • method merge
    Cases: ...
  • method flatten
    Cases: ...
  • method sum
    Cases: ...
  • method mean
    Cases: ...
  • method min
    Cases: ...
  • method max
    Cases: ...
  • method fill_left
    Cases: ...
  • method fill_right
    Cases: ...
  • method interleave
    Cases: ...
  • method select
    Cases: ...
  • method take
    Cases: ...
  • method take_right
    Cases: ...
  • method drop
    Cases: ...
  • method drop_right
    Cases: ...
  • method slice
    Cases: ...
  • method partition
    Cases: ...
  • method bisect
    Cases: ...
  • method trisect
    Cases: ...

For all: cases: empty, 1 item, 2+ items