Update runtime files

runtime/autoload/RstFold.vim

@@ -1,8 +1,12 @@
 " Author: Antony Lee <anntzer.lee@gmail.com>
 " Description: Helper functions for reStructuredText syntax folding
-" Last Modified: 2018-01-07
+" Last Modified: 2018-12-29
 
 function s:CacheRstFold()
+  if !g:rst_fold_enabled
+    return
+  endif
+
   let closure = {'header_types': {}, 'max_level': 0, 'levels': {}}
   function closure.Process(match) dict
     let curline = getcurpos()[1]
@@ -20,12 +24,18 @@ function s:CacheRstFold()
     let self.levels[curline] = self.header_types[key]
   endfunction
   let save_cursor = getcurpos()
+  let save_mark = getpos("'[")
   silent keeppatterns %s/\v^%(%(([=`:.'"~^_*+#-])\1+\n)?.{1,2}\n([=`:.'"~^_*+#-])\2+)|%(%(([=`:.''"~^_*+#-])\3{2,}\n)?.{3,}\n([=`:.''"~^_*+#-])\4{2,})$/\=closure.Process(submatch(0))/gn
   call setpos('.', save_cursor)
+  call setpos("'[", save_mark)
   let b:RstFoldCache = closure.levels
 endfunction
 
 function RstFold#GetRstFold()
+  if !g:rst_fold_enabled
+    return
+  endif
+
   if !has_key(b:, 'RstFoldCache')
     call s:CacheRstFold()
   endif
@@ -37,6 +47,10 @@ function RstFold#GetRstFold()
 endfunction
 
 function RstFold#GetRstFoldText()
+  if !g:rst_fold_enabled
+    return
+  endif
+
   if !has_key(b:, 'RstFoldCache')
     call s:CacheRstFold()
   endif