GPGEncrypt: Remove (file)encoding dance around file encryption

Changing &encoding when &fileencoding != &encoding causes two problems.

First, it's completely unsafe to change &encoding after vim is running,
since there may be characters that can't be translated from one encoding
to another, which can make vim crash.

Second, this actually loses information about the buffer's encoding.
When the encrypted file is opened later, it won't be in the same
encoding as before it was saved.  Changing user's data on them is
unacceptable.

Signed-off-by: James McCoy <jamessan@jamessan.com>

plugin/gnupg.vim

@@ -644,16 +644,6 @@ function s:GPGEncrypt()
   silent exe ':doautocmd '. auType .'Pre '. autocmd_filename
   call s:GPGDebug(2, 'called '. auType .'Pre autocommand for ' . autocmd_filename)
 
-  " store encoding and switch to a safe one
-  if (&fileencoding != &encoding)
-    let s:GPGEncoding = &encoding
-    let &encoding = &fileencoding
-    call s:GPGDebug(2, "encoding was \"" . s:GPGEncoding . "\", switched to \"" . &encoding . "\"")
-  else
-    let s:GPGEncoding = ""
-    call s:GPGDebug(2, "encoding and fileencoding are the same (\"" . &encoding . "\"), not switching")
-  endif
-
   " guard for unencrypted files
   if (exists("b:GPGEncrypted") && b:GPGEncrypted == 0)
     echohl GPGError
@@ -719,12 +709,6 @@ function s:GPGEncrypt()
   let cmd.redirect = '>' . s:shellescape(destfile, 1)
   silent call s:GPGExecute(cmd)
 
-  " restore encoding
-  if (s:GPGEncoding != "")
-    let &encoding = s:GPGEncoding
-    call s:GPGDebug(2, "restored encoding \"" . &encoding . "\"")
-  endif
-
   if (v:shell_error) " message could not be encrypted
     " Command failed, so clean up the tempfile
     call delete(destfile)