Problem:    Invalid memory access with for loop over NULL string.
Solution:   Make sure mb_ptr2len() consistently returns zero for NUL.
https://github.com/vim/vim/commit/f6d39c31d2177549a986d170e192d8351bd571e2

Problem:    K_SPECIAL may be escaped twice.
Solution:   Avoid double escaping. (closes vim/vim#10340)
https://github.com/vim/vim/commit/db08887f24d20be11d184ce321bc0890613e42bd

Copy test_regex_char_classes.vim from upstream to avoid future encoding
problems.

https://github.com/vim/vim/commit/80d7395dcfe96158428da6bb3d28a6eee1244e28

Problem:    Cannot save and restore a register properly.
Solution:   Add getreginfo() and make setreg() accept a dictionary. (Andy
            Massimino, closes vim/vim#3370)
https://github.com/vim/vim/commit/bb861e293e0170455184079fa537278754b07911

Cherry-pick eval.txt changes for getreginfo() from:
https://github.com/vim/vim/commit/6aa57295cfbe8f21c15f0671e45fd53cf990d404
https://github.com/vim/vim/commit/207f009326c8f878defde0e594d7d9ed9860106e

Problem:    Test_eval_stuff fails in normal terminal.
Solution:   Close the new window.
https://github.com/vim/vim/commit/61fbb3371ee1f6a02706f52fbe064608e159be7c

Required for v8.2.0598 to work.

Problem:    Test_eval is old style.
Solution:   Change some tests to a new style test.
https://github.com/vim/vim/commit/90455cfa87f84f16179c19241b034abbfa8b3c9a

Cherry-pick Test_setreg_basic changes from v8.2.0610.

Note that the old-style version of the tests (and the cherry-picked
changes) exist in legacy/eval_spec.lua; keep them as they've already
been Lua'd.

Required for v8.2.0924.

Port VimL's Blob type - vim-patch:8.1.{0735,0736,0738,0741,0742,0755,0756,0757,0765,0793,0797,0798,0802,1022,1023,1671},8.2.{0121,0184,0404,0521,0829,1473,1866,2712}