4.0.0

Changed

• Breaking: VChunk now cannot be empty.
• Breaking: A Version now guarantees NonEmpty chunks.
• Breaking: A Mess now guarantees NonEmpty chunks, and its structure has
  been significantly changed. Particularly, Mess values are now aware of the
  Int values they hold (when they do), as well as "revision" values of the
  pattern rXYZ.
• Comparison of Version values is more memory efficient.

Added

• Version now has an extra field, _vMeta :: [VChunk] for capturing
  "metadata" like Semver. This prevents otherwise nice-looking versions from
  being demoted to Mess.
• The MChunk type to accomodate the changes to Mess mentioned above.

Removed

• Breaking: Version no longer has a Monoid instance.

Fixed

• "" no longer parses in any way. #32
• Version strings with trailing whitespace no longer parse via versioning. #33
• Particular edge cases involving Mess comparisons. aura#646
• A particular edge case involving prereleases in Version comparisons. aura#586