modelines are enabled by default in most installations, but in cases where rhey
aren't, explicitly enable them. modern vim is protected against exploit by
running modelines in a sandbox and blocking expressions. they shouls be pretty
safe. nvim is planning to do more with it eventually to make it moreso.
" always save undo file for all file buffers
autocmd BufRead * set undofile
+" explicitly use modeline, even on systems where it's disabled by system vimrc
+autocmd BufRead set modeline
+" should be default disabled but just in case
+set nomodelineexpr
+
"" indent
" always use shiftwidth instead of tabsize
set smarttab