Log Message:
textproc/hs-doclayout: update to doclayout-0.5

## 0.5

  * Extract existing HasChars definition into a module
    Text.DocLayout.HasChars (Evan Silberman).

  * Add a `build` method to the signature of HasChars [API change]
    (Evan Silberman). This has a default definition, and is only needed with
    the ANSI renderer, so existing users should not need to add anything to
    their HasChars instances.

  * Introduce support for ANSI-styled output (Evan Silberman) [API change].
    `renderPlain` and `renderANSI` are now exported; the old `render`
    is a synonym of `renderPlain`.  In addition, various functions are
    exported to add ANSI formatting (including bold, italics,
    underline, strikeout, links, and colors) to a Doc. The Attributed
    type is also now exported.

  * Change type of Block constructor, replacing `[a]` with `[Attributed a]`,
    which carries a Font along with an inner string type [API change]
    (Evan Silberman).

  * Introduce FlatDocs and use them for rendering (Evan Silberman).
    This is an internal concept, not part of the public API.
    FlatDoc is an "intermediate representation" for the Doc \ 
"interpreter".
    The general design is that any Doc can be turned into a list of FlatDocs
    that carry equivalent information. The main point of doing this
    is to replace the nested Styled and Linked Docs, which form a more
    complicated tree structure than previously existed in DocLayout.

  * Deprecate `unfoldD`.