Disable ftdetect parts of some plugins, fixes #254

vim-polyglot discourages use of commands like:

autocmd BufRead *
autocmd BufNewFile *

And others that execute for every file / buffer opened.

config.vim

@@ -15,3 +15,14 @@ augroup filetypedetect
 augroup END
 
 let g:python_highlight_all = 1
+
+augroup filetypedetect
+  if v:version < 704
+    " NOTE: this line fixes an issue with the default system-wide lisp ftplugin
+    "       which didn't define b:undo_ftplugin on older Vim versions
+    "       (*.jl files are recognized as lisp)
+    autocmd BufRead,BufNewFile *.jl    let b:undo_ftplugin = "setlocal comments< define< formatoptions< iskeyword< lisp<"
+  endif
+  
+  autocmd BufRead,BufNewFile *.jl      set filetype=julia
+augroup END