Put vim state files in .cache

.vimrc

@@ -37,6 +37,11 @@ endfunction
 
 " ------ settings ------
 
+" xdg-ish settings
+set undodir=~/.cache/vim/undo,.
+set backupdir=~/.cache/vim/backup,.
+set directory=~/.cache/vim/swap,.
+
 " default indentation
 set shiftwidth=2
 set tabstop=4
@@ -44,7 +49,6 @@ set expandtab
 
 " permanent undo history
 set undofile
-set undodir=~/.vim/undo
 
 " allow switching buffers
 set hidden