Use hpath:find header link logic for HyWiki links

[matsl]

What

Use hpath:find header link logic for HyWiki links.

• hywiki.el (hywiki--org-link-html-format): Use
  `hpath:dashes-to-spaces-markup-anchor' to make header match target.
• test/hywiki-tests.el (hywiki-tests--action-key-moves-to-word-and-section-using-dash-to-space-conversion):
  Add test for headers with dashes.
  (hywiki-tests--published-html-links-to-word-and-section): Update test to
  the dash to space conversion in headers.

Why

hpath:find is a central part of both pathname headers (links) and
hywiki headers. Using a common scheme for both makes both usage and
implementation simpler.

In the published html links should go to the same header as within
HyWiki-mode.

Note

The dash to space conversion scheme means this types of links.

Space conversion scheme

"File#word-word-word" -> # word word word
"File#word word word" -> # word word word
"File#word word-word" -> # word word-word (Verbatim if both space and dash)

If File's mode is derived from prog-mode the header will be used
verbatim.

Headers that contains no space but a dash will not be possible to link
to.

HyWiki

For HyWiki this means, and copied from the new test:

WikiWord#first"                -> "* first"
WikiWord#header-one"           -> "* header one"
WikiWord#first one"            -> "* first"
(WikiWord#header one)"         -> "* header one"
WikiWord#header--two"          -> "* header  two"
(WikiWord#header--three)"      -> "* header  three"
WikiWord#header---four"        -> "* header   four"

Publishing

The generated pages will keep how they look, no dash substitution, but
the link will link to the header (target) as within hywiki-mode.