Co-authored-by: zeertzjq <zeertzjq@outlook.com>

- increase python line-length limit from 88 => 100.
- gen_help_html: fix bug in "tag" case (tbl_count => tbl_contains)

ref #15632
fix #18215
fix #18479
fix #20527
fix #20532

Co-authored-by: Ben Weedon <ben@weedon.email>

Problem:    Incomplete testing cursor position after change with 'linebreak'
            set.
Solution:   Add a test and move test cases together. (closes vim/vim#11313)
https://github.com/vim/vim/commit/30c0c467d6cc2a7af960ccb9002b50115b0e55cf

And remove unnecessary unsigned casts in fold marker comparison.

Problem:
- Docs HTML: "foo ~" headings (column_heading) are not aligned with
  their table columns/contents because the leading whitespace is not
  emitted.
- taglinks starting with hyphen like |-x| were not recognized.
- keycodes like `<foo>` and `CTRL-x` were not recognized.
- ToC is not scrollable.

Solution:
- Add ws() to the column_heading case.
- Update help parser to latest version
  - supports `keycode`
  - fixes for taglink, argument
- Update .toc CSS. https://github.com/neovim/neovim.github.io/issues/297

fix https://github.com/neovim/neovim.github.io/issues/297

Problem:    No space for command line when there is a tabline.
Solution:   Correct computation of where the command line should be.
            (closes vim/vim#11295)
https://github.com/vim/vim/commit/c9f5f73206272ccad0aa536854debc5f9781978a

vim-patch:9.0.0445: when opening/closing window text moves up/down

Problem:    When opening/closing window text moves up/down.
Solution:   Add the 'splitscroll' option.  When off text will keep its
            position as much as possible.
https://github.com/vim/vim/commit/29ab524358ba429bcf6811710afc97a978641f0b

vim-patch:9.0.0455: a few problems with 'splitscroll'

Problem:    A few problems with 'splitscroll'.
Solution:   Fix 'splitscroll' problems. (Luuk van Baal, closes vim/vim#11117)
https://github.com/vim/vim/commit/5ed391708a62b4ebaa84dd23e32a416e5c3383d9

vim-patch:9.0.0461: 'scroll' is not always updated

Problem:    'scroll' is not always updated.
Solution:   Call win_init_size() at the right place.
https://github.com/vim/vim/commit/470a14140bc06f1653edf26ab0b3c9b801080353

vim-patch:9.0.0465: cursor moves when cmdwin is closed when 'splitscroll' is off

Problem:    Cursor moves when cmdwin is closed when 'splitscroll' is off.
Solution:   Temporarily set 'splitscroll' when jumping back to the original
            window. (closes vim/vim#11128)
https://github.com/vim/vim/commit/e697d488901b6321ddaad68b553f0a434c97d849

vim-patch:9.0.0469: cursor moves if cmdwin is closed when 'splitscroll' is off

Problem:    Cursor moves if cmdwin is closed when 'splitscroll' is off.
Solution:   Skip win_fix_cursor if called when cmdwin is open or closing.
            (Luuk van Baal, closes vim/vim#11134)
https://github.com/vim/vim/commit/3735f11050616652525bf80b4fbcb2b3bfeab113

vim-patch:9.0.0478: test for 'splitscroll' takes too much time

Problem:    Test for 'splitscroll' takes too much time.
Solution:   Only test some of the combinations. (Luuk van Baal, closes vim/vim#11139)
https://github.com/vim/vim/commit/594f9e09cd68e6277b8aa08094405bc642c5792a

vim-patch:9.0.0486: text scrolled with 'nosplitscroll', autocmd win and help

Problem:    Text scrolled with 'nosplitscroll', autocmd win opened and help
            window closed.
Solution:   Skip win_fix_scroll() in more situations. (Luuk van Baal,
            closes vim/vim#11150)
https://github.com/vim/vim/commit/d5bc762dea1fd32fa04342f8149f95ccfc3b9709

vim-patch:9.0.0505: various problems with 'nosplitscroll'

Problem:    Various problems with 'nosplitscroll'.
Solution:   Fix 'nosplitscroll' problems. (Luuk van Baal, closes vim/vim#11166)
https://github.com/vim/vim/commit/faf1d412f5e3665021500b528c0e7301eb02bf0b

vim-patch:9.0.0555: scrolling with 'nosplitscroll' in callback changing curwin

Problem:    Scrolling with 'nosplitscroll' in callback changing curwin.
Solution:   Invalidate w_cline_row in the right place. (Luuk van Baal,
            closes vim/vim#11185)
https://github.com/vim/vim/commit/20e58561abc4116f3bfbafaef242d886dd77b303

vim-patch:9.0.0603: with 'nosplitscroll' folds are not handled correctly

Problem:    With 'nosplitscroll' folds are not handled correctly.
Solution:   Take care of closed folds when moving the cursor. (Luuk van Baal,
            closes vim/vim#11234)
https://github.com/vim/vim/commit/7c1cbb6cd437c6e0c3ccc05840cc931108b4a60a

vim-patch:9.0.0605: dump file missing

Problem:    Dump file missing.
Solution:   Add the missing dump file. (issue vim/vim#11234)
https://github.com/vim/vim/commit/439a2ba1749463718b6ce1e1375b68c7b7cff808

vim-patch:9.0.0647: the 'splitscroll' option is not a good name

Problem:    The 'splitscroll' option is not a good name.
Solution:   Rename 'splitscroll' to 'splitkeep' and make it a string option,
            also supporting "topline". (Luuk van Baal, closes vim/vim#11258)
https://github.com/vim/vim/commit/13ece2ae1d09009d3fb8acf858c288e7848ecdac

vim-patch:9.0.0667: ml_get error when 'splitkeep' is "screen"

Problem:    ml_get error when 'splitkeep' is "screen". (Marius Gedminas)
Solution:   Check the botline is not too large. (Luuk van Baal,
            closes vim/vim#11293, closes vim/vim#11292)
https://github.com/vim/vim/commit/346823d3e5668b99d2c2fd920e7f215e21ad3ea7