feat: use g:cursorhold_updatetime instead of &updatetime

Decoupling updatetime from CursorHold allows to have a short cursorhold
updatetime without writing the swap on the disk too often.
See :h updatetime

README.md

@@ -1,15 +1,18 @@
-Fix Neovim's CursorHold perf bug
+Fix CursorHold Performance
 =================================
 
 Rationale
 ---------
 
-Neovim's implementations of **CusorHold** and **CursorHoldI** autocmd events have a [performance bug][issue]
-which causes slowdowns, and sometimes, don't even trigger those events.
+This plugin exists for two reasons:
+  1. fix neovim **CusorHold** and **CursorHoldI** autocmd events [performance bug][issue]
+  2. decouple **updatetime** from **CusorHold** and **CursorHoldI** (works for Vim and Neovim)
 
-This plugin fixes this by manually triggering those.
+1., fixes slowdowns and untriggered events
 
-This will result in more snapiness for plugins using those events, such as:
+2., you can now use small delays for **CursorHold** without writing the swap file 10x/sec (set :h updatetime)
+
+This will result in more snappiness for plugins using those events, such as:
 **coc.nvim**, **vim-gutter**, **tagbar**, **vim-devicons**, **vim-polyglot**, etc.
 
 Installation
@@ -19,6 +22,14 @@ Make sure to have the following plugins in your **vimrc**:
 ```vim
 Plug 'antoinemadec/FixCursorHold.nvim'
 ```
+Configuration
+---------
+
+```vim
+" in millisecond, used for both CursorHold and CursorHoldI,
+" use updatetime instead if not defined
+let g:cursorhold_updatetime = 100
+```
 
 License
 -------

plugin/fix_cursorhold_nvim.vim

@@ -1,6 +1,6 @@
 " Maintainer:   Antoine Madec <aja.madec@gmail.com>
 
-if exists('g:loaded_fix_cursorhold_nvim') || !has('nvim')
+if exists('g:loaded_fix_cursorhold_nvim')
   finish
 else
   let g:loaded_fix_cursorhold_nvim = 'yes'
@@ -31,5 +31,6 @@ function s:CursorHoldTimer(mode) abort
     call timer_stop(g:fix_cursorhold_nvim_timer)
   endif
   let cb = a:mode == "n" ? 's:CursorHold_Cb' : 's:CursorHoldI_Cb'
-  let g:fix_cursorhold_nvim_timer = timer_start(&updatetime, function(cb))
+  let t = get(g:, 'cursorhold_updatetime', &updatetime)
+  let g:fix_cursorhold_nvim_timer = timer_start(t, function(cb))
 endfunction