Problem:  ml_get error when scrolling after delete
Solution: mark topline to be validated in main_loop
          if it is larger than current buffers line
          count

reset_lnums() is called after e.g. TextChanged autocommands and it may
accidentally cause curwin->w_topline to become invalid, e.g. if the
autocommand has deleted some lines.

So verify that curwin->w_topline points to a valid line and if not, mark
the window to have w_topline recalculated in main_loop() in
update_topline() after reset_lnums() returns.

fixes: vim/vim#13568
fixes: vim/vim#13578

https://github.com/vim/vim/commit/c4ffeddfe5bd1824650e9b911ed9245bf56c69e3

The error doesn't happen in Nvim because Nvim triggers TextChanged after
calling update_topline().

Co-authored-by: Christian Brabandt <cb@256bit.org>

Problem:  TextChangedI may not always trigger
Solution: trigger it in more cases: for insert/
          append/change operations, and when
          opening a new line,

fixes: vim/vim#13367
closes: vim/vim#13375

https://github.com/vim/vim/commit/4bca4897a12dfb91b3b27e3083fd5f370bd857d1

Co-authored-by: Christian Brabandt <cb@256bit.org>

Problem:  `TextChangedI` can trigger on entering Insert mode if there
          was previously a change not in Insert mode.
Solution: Make it trigger only when text is actually changed in Insert
          mode.

closes: vim/vim#13265
closes: vim/vim#13338

https://github.com/vim/vim/commit/d7ae263af8f6a2da55ce3702d18c53ab1418bca7

Co-authored-by: Evgeni Chasnovski <evgeni.chasnovski@gmail.com>

Problem:    TextChanged does not trigger after TextChangedI.
Solution:   Store the tick separately for TextChangedI. (Christian Brabandt,
            closes vim/vim#8968, closes vim/vim#8932)

https://github.com/vim/vim/commit/db3b44640d69ab27270691a3cab8d83cc93a0861

Co-authored-by: Christian Brabandt <cb@256bit.org>