add VimagitLeaveCommit User autocmd and add tw example

ref #140

README.md

@@ -294,7 +294,7 @@ absolute path.
 *Note:* `g:magit_last_updated_buffer` will be updated and VimagitUpdateFile event will
 be raised only if the buffer is currently opened in vim.
 
-##### VimagitCommitEnter
+##### VimagitEnterCommit
 
 This event is raised when the commit section opens and the cursor is
 placed in this section. For example, the user may want to go straight into
@@ -304,6 +304,17 @@ insert mode when committing, defining this autocmd in its vimrc:
   autocmd User VimagitEnterCommit startinsert
 ```
 
+##### VimagitLeaveCommit
+
+This event is raised when the commit section is closed, because the user
+finished to write its commit message or canceled it. For example, the user wants
+to set the |textwidth| of the vimagit buffer while editing a commit message,
+   defining these |autocmd| in vimrc:
+```
+  autocmd User VimagitEnterCommit setlocal textwidth=72
+  autocmd User VimagitLeaveCommit setlocal textwidth=0
+```
+
 #### Autocmd example
 
 The following example calls the vim-gitgutter refresh function on a specific

doc/vimagit.txt

@@ -341,15 +341,26 @@ absolute path.
 Note: |g:magit_last_updated_buffer| will be updated and VimagitUpdateFile event will
 be raised only if the buffer is currently opened in vim.
 
-VimagitCommitEnter                                  *vimagit-VimagitCommitEnter*
+VimagitEnterCommit                                  *vimagit-VimagitEnterCommit*
 
 This event is raised when the commit section opens and the cursor is
 placed in this section. For example, the user may want to go straight into
-insert mode when committing, defining this |autocmd| in its vimrc:
+insert mode when committing, defining this |autocmd| in vimrc:
 >
   autocmd User VimagitEnterCommit startinsert
 <
 
+VimagitLeaveCommit                                  *vimagit-VimagitLeaveCommit*
+
+This event is raised when the commit section is closed, because the user
+finished to write its commit message or canceled it. For example, the user
+wants to set the |textwidth| of the vimagit buffer while editing a commit
+message, defining these |autocmd| in vimrc:
+>
+  autocmd User VimagitEnterCommit setlocal textwidth=72
+  autocmd User VimagitLeaveCommit setlocal textwidth=0
+<
+
 Autocmd example                                        *vimagit-autocmd_example*
 ---------------
 

plugin/magit.vim

@@ -1112,6 +1112,9 @@ function! magit#commit_command(mode)
 			" when we do commit, it is prefered ot commit the way we prepared it
 			" (.i.e normal or amend), whatever we commit with CC or CA.
 			call <SID>mg_git_commit(b:magit_current_commit_mode)
+			if exists('#User#VimagitLeaveCommit')
+				doautocmd User VimagitLeaveCommit
+			endif
 		else
 			let b:magit_current_commit_mode=a:mode
 			let b:magit_commit_newly_open=1
@@ -1138,6 +1141,9 @@ function! magit#close_commit()
 
   let b:magit_current_commit_mode=''
   let b:magit_current_commit_msg=[]
+  if exists('#User#VimagitLeaveCommit')
+	  doautocmd User VimagitLeaveCommit
+  endif
   call magit#update_buffer()
 endfunction