implement large cache fix in core

// use the smaller size for testing.
	const CHUNK_SIZE  = 100000; // Arbitrary size until we decide
//	    const CHUNK_SIZE  = 65535; // MySQL TEXT Type

/**
	         * this code will set up pre_option and pre_update filter for the
	         * large cache fix
	         **/
	        foreach( Ninja_Forms()->form()->get_forms() as $form ){
//		        if( ! get_option( 'nf_form_' . $form->get_id() . '_chunks', false ) ) continue;
		        add_filter( 'pre_option_nf_form_' . $form->get_id(),
			        'WPN_Helper::pre_option', 10, 1 );
		        add_filter( 'pre_update_option_nf_form_' . $form->get_id(),
			        'WPN_Helper::pre_update_option', 10, 2 );
	        }
         
// Helper.php
          public static function pre_option( $value )
	{
		$filter = str_replace( 'pre_option_', '', current_filter() );
		$flag = $filter . '_chunks';
		// if there is no nf_form_x_chunks option, we have not chunked
		// this for, carry on
		if( ! get_option( $flag ) ) return $value;
		$new_value = '';
		// if we have chunk'd it, get the list of chunks
		$options = explode( ',', get_option( $flag ) );

		//get the option value of each chunk and concat them into the form
		foreach( $options as $option ){
			$new_value .= get_option( $option );
		}
		return maybe_unserialize( $new_value );
	}

	public static function pre_update_option( $new_value, $old_value )
	{
		if( is_array( $new_value ) ){
			$tmp_new_value = maybe_serialize( $new_value );
		}
		// if serialized form length is less than chunk size, then carry on
		if ( self::CHUNK_SIZE > strlen($tmp_new_value) ) return $new_value;
		// otherwise, get the name of the option we want to set
		$filter = str_replace( 'pre_update_option_', '', current_filter() );
		$new_options = array();

		// create the chunks
		$chunks = explode("\r\n", chunk_split($tmp_new_value, self::CHUNK_SIZE));
		// create chunk option, eg. nf_form_1_0, nf_form_1_1...
		foreach ($chunks as $key => $value) {
			if( '' == $value ) continue;
			$option = $filter . '_' . $key;
			update_option($option, $value, false);
			$new_options[] = $option;
		}
		// set the chunk option with a value of the list of the chunks
		update_option($filter . '_chunks', implode(',', $new_options));
		return $new_value;
	}
  
  // AJAX/Controllers/Form.php
  
  // if we've had chunked cache in the past, remove the reference
        if( get_option( 'nf_form_' . $form->get_id() . '_chunks', false ) ) {
        	delete_option( 'nf_form_' . $form->get_id() . '_chunks' );
        }
  
  // attach filters that might enable chunking if needed.
	    add_filter( 'pre_option_nf_form_' . $form->get_id(),
		    'WPN_Helper::pre_option', 10, 1 );
	    add_filter( 'pre_update_option_nf_form_' . $form->get_id(),
		    'WPN_Helper::pre_update_option', 10, 2 );