* Added `embed_data_files` flag. (not yet used)
* Shared no longer exports `findDataFile`.
* `readDataFile` now returns a strict bytestring.
* Shared now exports `readDataFileUTF8` which returns a string like
the old `readDataFile`.
* Rewrote modules to use new data file functions and to avoid
using functions from Paths_pandoc directly.
* Depend on text.
* Expose Text.Pandoc.UTF8.
* Text.Pandoc.UTF8 now exports toString, fromString,
toStringLazy, fromStringLazy.
* These are used instead of the old utf8-string functions.
