ext_tables.php

<?php
if (!defined('TYPO3_MODE')) {
    die ('Access denied.');
}

call_user_func(
    function ($extKey) {

        // Build extension name vars - used for plugin registration, flexforms and similar
        $extensionName = \TYPO3\CMS\Core\Utility\GeneralUtility::underscoredToUpperCamelCase($extKey);
        $pluginSignature = strtolower($extensionName) . '_pi1';

        \TYPO3\CMS\Extbase\Utility\ExtensionUtility::registerPlugin(
            $extKey,
            'Pi1',
            'WS Flexslider'
        );

        \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addStaticFile($extKey, 'Configuration/TypoScript',
            'Flexslider');


        \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::allowTableOnStandardPages('tx_wsflexslider_domain_model_image');
        \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addLLrefForTCAdescr(
            'tx_wsflexslider_domain_model_image',
            'EXT:ws_flexslider/Resources/Private/Language/locallang_csh_image.xlf');


        $GLOBALS['TCA']['tt_content']['types']['list']['subtypes_excludelist'][$pluginSignature] = 'layout,select_key,pages,recursive';
        $GLOBALS['TCA']['tt_content']['types']['list']['subtypes_addlist'][$pluginSignature] = 'tx_wsflexslider_images,pi_flexform';

        \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPiFlexFormValue($pluginSignature,
            'FILE:EXT:' . $extKey . '/Configuration/FlexForm/Flexslider.xml');


    },
    'ws_flexslider'
);