+ Use `\phantomsection` and `\label` instead of `\hypertarget`.
+ Use `\hyperref` for LaTeX internal links, `\hyperlink` for
beamer (since `\hyperref` doesn't seem to work).
Closes#9022.
We no longer wrap section headings in a `\hypertarget`.
This is unnecessary (hyperref creates an anchor based on the
label) and it interferes with tagging.
In addition, we now use `\hyperref` rather than `\hyperlink`
for internal links.
Currently `\hypertarget` is still being used for link anchors
not on headings.
Closes#8744. Thanks to @u-fischer.
The fix to #6030 actually changed behavior, so that the
2D nesting occurred at slide level N-1 and N, instead of
at the top-level section. This commit restores the 2.7.3 behavior.
If there are more than 2 levels, the top level is horizontal
and the rest are collapsed to vertical.
Closes#6032.
John MacFarlane