The `raw_attribute` will be used to mark raw bits, even HTML
and LaTeX, and even when `raw_html` and `raw_tex` are enabled,
as they are by default.
To get the old behavior, disable `raw_attribute` in the writer.
Closes#4311.
* XML.toEntities: changed type to Text -> Text.
* Shared.tabFilter -- fixed so it strips out CRs as before.
* Modified writers to take Text.
* Updated tests, benchmarks, trypandoc.
[API change]
Closes#3731.
