Merge from vendor branch TNF:

Merge from vendor branch TNF:
Import tex-soul-2.4 as print/tex-soul.

Provides hyphenatable spacing out (letterspacing), underlining, striking
out, etc., using the TeX hyphenation algorithm to find the proper
hyphens automatically. The package also provides a mechanism that can be
used to implement similar tasks, that have to treat text syllable by
syllable. This is shown in two examples. The package itself does not
support UTF-8 input in ordinary (PDF)LaTeX; some UTF-8 support is
offered by package soulutf8.