Don't set tabstop in shell buffers (#224)

:FZF opens a terminal in the same window as the current buffer, and
setbufvar(tabstop) affects the cursor position in the current buffer
as well as the cursor position in the terminal buffer.

To avoid that, don't set tabstop in terminal windows running shells.

plugin/editorconfig.vim

@@ -454,7 +454,8 @@ function! s:ApplyConfig(bufnr, config) abort
         endif
     endif
 
-    if s:IsRuleActive('tab_width', a:config)
+    " Set tabstop.  Skip this for terminal buffers, e.g., :FZF (#224).
+    if s:IsRuleActive('tab_width', a:config) && bufname(l:bufnr) !~# '^!\w*sh$'
         let l:tabstop = str2nr(a:config["tab_width"])
         call setbufvar(a:bufnr, '&tabstop', l:tabstop)
     else