Handle setopt shwordsplit (#89)

This uses `emulate -L zsh` (as a more broad approach to `setopt
localtoptions noshwordsplit`, or quoting things) in the entry points to
zsh-autoenv.

Fixes https://github.com/Tarrasch/zsh-autoenv/issues/75

tests/setup.zsh

@@ -28,6 +28,7 @@ fi
 
 # Add file ($1), version ($2), and optional hash ($3) to authentication file.
 test_autoenv_add_to_env() {
+  emulate -L zsh
   [[ -d ${AUTOENV_AUTH_FILE:h} ]] || mkdir -p ${AUTOENV_AUTH_FILE:h}
   _autoenv_deauthorize $1
   {