Allow loading the plugin in the background

If zle is already active (plugin has been loaded in the background),
just start the widgets and set up the automatic re-binding (if manual
rebind has not been specified).

See GitHub issue #481

src/start.zsh

@@ -18,6 +18,14 @@ _zsh_autosuggest_start() {
 	_zsh_autosuggest_bind_widgets
 }
 
-# Start the autosuggestion widgets on the next precmd
-autoload -Uz add-zsh-hook
-add-zsh-hook precmd _zsh_autosuggest_start
+# Mark for auto-loading the functions that we use
+autoload -Uz add-zsh-hook is-at-least
+
+# If zle is already running, go ahead and start the autosuggestion widgets.
+# Otherwise, wait until the next precmd.
+if zle; then
+	_zsh_autosuggest_start
+	(( ! ${+ZSH_AUTOSUGGEST_MANUAL_REBIND} )) && add-zsh-hook precmd _zsh_autosuggest_start
+else
+	add-zsh-hook precmd _zsh_autosuggest_start
+fi

src/strategies/completion.zsh

@@ -45,8 +45,6 @@ _zsh_autosuggest_capture_completion_widget() {
 zle -N autosuggest-capture-completion _zsh_autosuggest_capture_completion_widget
 
 _zsh_autosuggest_capture_setup() {
-	autoload -Uz is-at-least
-
 	# There is a bug in zpty module in older zsh versions by which a
 	# zpty that exits will kill all zpty processes that were forked
 	# before it. Here we set up a zsh exit hook to SIGKILL the zpty

zsh-autosuggestions.zsh

@@ -541,8 +541,6 @@ _zsh_autosuggest_capture_completion_widget() {
 zle -N autosuggest-capture-completion _zsh_autosuggest_capture_completion_widget
 
 _zsh_autosuggest_capture_setup() {
-	autoload -Uz is-at-least
-
 	# There is a bug in zpty module in older zsh versions by which a
 	# zpty that exits will kill all zpty processes that were forked
 	# before it. Here we set up a zsh exit hook to SIGKILL the zpty
@@ -853,6 +851,14 @@ _zsh_autosuggest_start() {
 	_zsh_autosuggest_bind_widgets
 }
 
-# Start the autosuggestion widgets on the next precmd
-autoload -Uz add-zsh-hook
-add-zsh-hook precmd _zsh_autosuggest_start
+# Mark for auto-loading the functions that we use
+autoload -Uz add-zsh-hook is-at-least
+
+# If zle is already running, go ahead and start the autosuggestion widgets.
+# Otherwise, wait until the next precmd.
+if zle; then
+	_zsh_autosuggest_start
+	(( ! ${+ZSH_AUTOSUGGEST_MANUAL_REBIND} )) && add-zsh-hook precmd _zsh_autosuggest_start
+else
+	add-zsh-hook precmd _zsh_autosuggest_start
+fi