Problem:    The mouse code is spread out.
Solution:   Move all the mouse code to mouse.c. (Yegappan Lakshmanan,
            closes vim/vim#4959)

https://github.com/vim/vim/commit/b20b9e14ddd8db111e886ad0494e15b955159426

Also move getmousepos() there.

N/A patches for version.c:

vim-patch:8.1.2070: mouse code is spread out

Problem:    Mouse code is spread out.
Solution:   Move mouse terminal code parsing to mouse.c. (Yegappan Lakshmanan,
            closes vim/vim#4966)

https://github.com/vim/vim/commit/b8ff5c271ee5dcef6f63436b77e228e062ff9a0e

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

Problem:    Cannot check the current state.
Solution:   Add the state() function.

https://github.com/vim/vim/commit/0e57dd859ecb1e8a3b91509d2f4343e839340eb8

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

- eval.lua is now the source of truth.

- Formatting is much more consistent.

- Fixed Lua type generation for polymorphic functions (get(), etc).

- Removed "Overview" section from builtin.txt
  - Can generate this if we really want it.

- Moved functions from sign.txt and testing.txt into builtin.txt.

- Removed the *timer* *timers* tags since libuv timers via vim.uv should be preferred.

- Removed the temp-file-name tag from tempname()

- Moved lueval() from lua.txt to builtin.txt.

* Fix indent

* fixup!

* fixup! fixup!

* fixup! better tag formatting

* fixup: revert changes no longer needed

* fixup! CI

---------

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

Problem:    The evalfunc.c file is too big.
Solution:   Move undo functions to undo.c.  Move cmdline functions to
            ex_getln.c.  Move some container functions to list.c.

https://github.com/vim/vim/commit/08c308aeb5e7dfa18fa61f261b0bff79517a4883

Undo functions only. Cmdline functions have already been moved.
A lot of container functions have been added to eval/funcs.c instead of
list.c in previously ported Vim 8.2.x patches, so deal with that later.

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

Problem:    Using inclusive index for slice is not always desired.
Solution:   Add the slice() method, which has an exclusive index. (closes
            vim/vim#7408)

https://github.com/vim/vim/commit/6601b62943a19d4f8818c3638440663d67a17b6a

Cherry-pick a line in docs added later.

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

Problem:    Functions for string manipulation are spread out.
Solution:   Move string related functions to a new source file. (Yegappan
            Lakshmanan, closes vim/vim#8470)

https://github.com/vim/vim/commit/a2438132a675be4dde3acbdf03ba1fdb2f09427c

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

problem: the api of vim.mpack is not compatible with a system provided mpack
solution: don't require 'mpack' directly from the system path

libnvim couldn't be easily used in C++ due to the use of reserved keywords.

Additionally, add explicit casts to *alloc function calls used in inline
functions, as C++ doesn't allow implicit casts from void pointers.

Problem:    Cannot easily get the list of sourced scripts.
Solution:   Add the getscriptinfo() function. (Yegappan Lakshmanan,
            closes vim/vim#10957)

https://github.com/vim/vim/commit/f768c3d19c518822d89dec4cc3947ddeea249316

Cherry-pick usr_41.txt change from a later runtime update.

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