Reapply "Revert persistent undo and swap file disable stuff"

This reverts commit 7623ee423f.

nvim/.config/nvim/init.lua

@@ -75,16 +75,6 @@ vim.cmd [[
     set errorformat^=[----]\ %f:%l:\ %m
 ]]
 
-vim.o.backup = false
-vim.o.writebackup = false
-vim.o.swapfile = false
-vim.o.autoread = true
-vim.o.undofile = true
-vim.o.undodir = vim.fn.expand("~/.vim/neoundodir")
-if vim.fn.isdirectory(vim.o.undodir) == 0 then
-  vim.fn.mkdir(vim.o.undodir, "p")
-end
-
 vim.keymap.set('n', ',cf', function()
     local qf = vim.fn.getqflist()
     for i, item in ipairs(qf) do

vim/.vimrc

@@ -43,19 +43,6 @@ nnoremap ,x <C-x>
 
 set autoindent
 set cursorline
-
-set nobackup
-set nowritebackup
-set noswapfile
-set autoread
-set undofile
-set undodir=~/.vim/undodir
-if !isdirectory(expand('~/.vim/undodir'))
-    call mkdir(expand('~/.vim/undodir'), 'p')
-endif
-
-set undodir=~/.vim/undodir
-set undofile
 set errorformat^=[----]\ %f:%l:\ %m
 set expandtab
 set exrc