This covers issues referenced from #245 or labelled "feature:redrawhook" or "widget-wrapping".  See #749 for details.

Test case: See the first comment of issue #295.

Before:
num  calls                time                       self            name
-----------------------------------------------------------------------------------
 1)   14         284.67    20.33   82.84%    284.67    20.33   82.84%  _zsh_highlight_highlighter_brackets_paint
 2)   15         313.72    20.91   91.30%     26.62     1.77    7.75%  _zsh_highlight
 3)   14         318.68    22.76   92.74%      7.41     0.53    2.16%  _zsh_highlight_call_widget

After:
num  calls                time                       self            name
-----------------------------------------------------------------------------------
 1)   15          57.25     3.82   45.33%     28.30     1.89   22.41%  _zsh_highlight
 2)   14          81.96     5.85   64.90%     27.02     1.93   21.40%  _zsh_highlight_call_widget
 3)   14          26.31     1.88   20.84%     26.31     1.88   20.84%  _zsh_highlight_highlighter_brackets_paint
 4)    2          10.66     5.33    8.44%      8.97     4.49    7.10%  VCS_INFO_formats
 5)    2          25.92    12.96   20.52%      7.72     3.86    6.11%  VCS_INFO_get_data_git

(That's not in my everyday configuration but in my minimal testing
setup, which runs vcs_info with the default settings.)

Fixes #418 (interoperability issue with other plugins).

Fixes #585.

Closes #607 #649 #704

The fix is to exempt such aliases from the empty commands sanity check.

The great-grandparent commit, "a3ae74 'main': Fix the last commit's bug
concerning parameter elision not happening in redirects in command
position.", is not added because it's not a change with respect
to 0.7.1.

In those versions of zsh, «[[ -o nosuchoption ]]» is regarded as
a syntax error.  In newer zsh versions, it merely returns non-zero
(specifically, it returns 3, unlike «[[ -o unsetoption ]]» which
returns 1).

Fixes #732.
Fixes #733.

Fixes #461.

Fixes #430.

This is not perfect: we don't try to detect cases such as «$((ls); (ls))»,
which look like arithmetic expansions but are in fact command substitutions.

Fixes part of #607.

Introduces #704.

Fixes #694.

Fixes #583.

Fixes #582.

Fixes #676.