Problem:    screenpos() column result in fold may be too small.
Solution:   Add space of 'number', sign column, etc. (closes vim/vim#11715)

https://github.com/vim/vim/commit/ba2d19193201277397c25c1f5a134ea042542555

Problem:    screenpos() does not count filler lines for diff mode.
Solution:   Add filler lines. (closes 11658)

https://github.com/vim/vim/commit/1cb16c3a20a9d17df1a8dc3813ef64dc98e42637

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    ml_get error when using screenpos().
Solution:   Give an error for the line number. (closes vim/vim#11661)

https://github.com/vim/vim/commit/99d19438cabaf13074229d9a32e3a4af9ce98744

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    screenpos() does not handle a position in a closed fold.
Solution:   Check if the position is inside a closed fold. (closes vim/vim#9778)

https://github.com/vim/vim/commit/4556a2e8681c5c98fb4c7ca0a016924a69b4452a

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    screenpos() has non-zero row for invisible text.
Solution:   Only add the window row when the text is visible. (closes vim/vim#9618)

https://github.com/vim/vim/commit/7924a17791217d50be5a91989a9641bf68e7a735

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    screenpos() is wrong when the last line is partially visible and
            'display' is "lastline".
Solution:   Also compute the position for a partially visible line.
            (closes vim/vim#8599)

https://github.com/vim/vim/commit/189663bdac1156237c49925f77bd197c1bdea12c

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    col() and charcol() only work for the current window.
Solution:   Add an optional winid argument. (Yegappan Lakshmanan,
            closes vim/vim#11466, closes vim/vim#11461)

https://github.com/vim/vim/commit/4c8d2f02b3ce037bbe1d5ee12887e343c6bde88f

Cherry-pick test_functions.vim change from patch 8.2.0633.

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

Problem:    Wrong column when calling setcursorcharpos() with zero lnum.
Solution:   Set the line number before calling buf_charidx_to_byteidx().
            (closes vim/vim#11329)
https://github.com/vim/vim/commit/79f234499b6692cc16970b7455bc9b002242632f

Problem:    Vim9: no error when using "2" for a line number.
Solution:   Give an error message if the line number is invalid. (closes vim/vim#7492)
https://github.com/vim/vim/commit/9a963377b4811e4e0419ec8825856ff4b01331ac

N/A patches for version.c:

vim-patch:8.2.1465: Vim9: subscript not handled properly

Problem:    Vim9: subscript not handled properly.
Solution:   Adjust error message.  Remove dead code.  Disallow string to
            number conversion in scripts.
https://github.com/vim/vim/commit/56acb0943ede35cd9d2f6667cde2442819ccbf59

Problem:    There is no way to get the byte index from a virtual column.
Solution:   Add virtcol2col(). (Yegappan Lakshmanan, closes vim/vim#10477,
            closes vim/vim#10098)
https://github.com/vim/vim/commit/5a6ec10cc80ab02eeff644ab19b82312630ea855

Cherry-pick tv_check_for_number_arg() from Vim.
Cherry-pick pathshorten() doc change.