Fix moving cursor to end of buffer when suggestion accepted

$max_cursor_pos in this case was not the correct value to use. It was
calculated based on the old length of the $BUFFER. After the suggestion
is accepted, we need to recalculate the new max cursor length and use it
to set the $CURSOR.

Fixes issue #452. Follow-up to issue #302 (PR #450).

zsh-autosuggestions.zsh

@@ -398,7 +398,11 @@ _zsh_autosuggest_accept() {
 		unset POSTDISPLAY
 
 		# Move the cursor to the end of the buffer
-		CURSOR=${max_cursor_pos}
+		if [[ "$KEYMAP" = "vicmd" ]]; then
+			CURSOR=$(($#BUFFER - 1))
+		else
+			CURSOR=$#BUFFER
+		fi
 	fi
 
 	_zsh_autosuggest_invoke_original_widget $@