`nvim_get_option_value` and `nvim_set_option_value` better handle
unsetting local options. For instance, this is currently not possible:
vim.bo.tagfunc = nil
This does not work because 'tagfunc' is marked as "local to buffer" and
does not have a fallback global option. However, using :setlocal *does*
work as expected
:setlocal tagfunc=
`nvim_set_option_value` behaves more like :set and :setlocal (by
design), so using these as the underlying API functions beneath vim.bo
and vim.wo makes those two tables act more like :setlocal. Note that
vim.o *already* uses `nvim_set_option_value` under the hood, so that
vim.o behaves like :set.
87a68b6a3a
