Hardcoding a charset causes trouble when porting Vim patches.
I previously tried to unset "charset" for certain file extensions, but
vim-patch.sh can generate more files, and automatically detecting file
encoding is more correct anyway.

There  are *.vim and *.po files ported from Vim that use a non-UTF-8 encoding.

We established a while ago that 100 chars is our line length for both C
and Lua. Not all editorconfig plugins support the "max_line_length"
option, but many do (including all of the ones available for Vim/Neovim
to the best of my knowledge).

Vim patches may include tabs in Vimscript test files.
editorconfig uses "indent_size" for tabs if "tab_width" is unset
so the user sees 2-width tabs.

According to
https://github.com/editorconfig/editorconfig/wiki/EditorConfig-Properties
the possible values of the charset property are "latin1", "utf-8",
"utf-16be", "utf-16le", or "utf-8-bom" (case insensitive), not "utf_8"

It breaks https://github.com/sgur/vim-editorconfig/ for example.