A blob is used as a sequence of bytes and usually accessed individually,
not as as a NUL-terminuated string, so uint8_t should be better.

Not sure about ga_append(), but using uint8_t leads to fewer casts.

Work on https://github.com/neovim/neovim/issues/459

Allow Include What You Use to remove unnecessary includes and only
include what is necessary. This helps with reducing compilation times
and makes it easier to visualise which dependencies are actually
required.

Work on https://github.com/neovim/neovim/issues/549, but doesn't close
it since this only works fully for .c files and not headers.

* refactor: replace char_u with char

Work on https://github.com/neovim/neovim/issues/459

Problem:    The eval.c file is too big.
Solution:   Move code related to variables to evalvars.c. (Yegappan
            Lakshmanan, closes vim/vim#4868)
https://github.com/vim/vim/commit/0522ba0359c96a8c2a4fc8fca0d3b58e49dda759

Name the new file eval/vars.c instead.

Work on https://github.com/neovim/neovim/issues/459

Work on https://github.com/neovim/neovim/issues/459

Problem:    Giving error messages is not flexible.
Solution:   Add semsg().  Change argument from "char_u *" to "char *", also
            for msg() and get rid of most MSG macros. (Ozaki Kiichi, closes
            vim/vim#3302)  Also make emsg() accept a "char *" argument.  Get rid of
            an enormous number of type casts.
https://github.com/vim/vim/commit/f9e3e09fdc93be9f0d47afbc6c7df1188c2a5a0d